how to cite facts in a research paper

Citing sources: Overview

• Citation style guides

Manage your references

Use these tools to help you organize and cite your references:

• Citation Management and Writing Tools

If you have questions after consulting this guide about how to cite, please contact your advisor/professor or the writing and communication center .

Why citing is important

It's important to cite sources you used in your research for several reasons:

• To show your reader you've done proper research by listing sources you used to get your information
• To be a responsible scholar by giving credit to other researchers and acknowledging their ideas
• To avoid plagiarism by quoting words and ideas used by other authors
• To allow your reader to track down the sources you used by citing them accurately in your paper by way of footnotes, a bibliography or reference list

About citations

Citing a source means that you show, within the body of your text, that you took words, ideas, figures, images, etc. from another place.

Citations are a short way to uniquely identify a published work (e.g. book, article, chapter, web site).  They are found in bibliographies and reference lists and are also collected in article and book databases.

Citations consist of standard elements, and contain all the information necessary to identify and track down publications, including:

• author name(s)
• titles of books, articles, and journals
• date of publication
• page numbers
• volume and issue numbers (for articles)

Citations may look different, depending on what is being cited and which style was used to create them. Choose an appropriate style guide for your needs.  Here is an example of an article citation using four different citation styles.  Notice the common elements as mentioned above:

Author - R. Langer

Article Title - New Methods of Drug Delivery

Source Title - Science

Volume and issue - Vol 249, issue 4976

Publication Date - 1990

Page numbers - 1527-1533

American Chemical Society (ACS) style:

Langer, R. New Methods of Drug Delivery. Science 1990 , 249 , 1527-1533.

IEEE Style:

R. Langer, " New Methods of Drug Delivery," Science , vol. 249 , pp. 1527-1533 , SEP 28, 1990 .

American Psychological Association   (APA) style:

Langer, R. (1990) . New methods of drug delivery. Science , 249 (4976), 1527-1533.

Modern Language Association (MLA) style:

Langer, R. " New Methods of Drug Delivery." Science 249.4976 (1990) : 1527-33.

What to cite

You must cite:

• Facts, figures, ideas, or other information that is not common knowledge

Publications that must be cited include:  books, book chapters, articles, web pages, theses, etc.

Another person's exact words should be quoted and cited to show proper credit 

When in doubt, be safe and cite your source!

Avoiding plagiarism

Plagiarism occurs when you borrow another's words (or ideas) and do not acknowledge that you have done so. In this culture, we consider our words and ideas intellectual property; like a car or any other possession, we believe our words belong to us and cannot be used without our permission.

Plagiarism is a very serious offense. If it is found that you have plagiarized -- deliberately or inadvertently -- you may face serious consequences. In some instances, plagiarism has meant that students have had to leave the institutions where they were studying.

The best way to avoid plagiarism is to cite your sources - both within the body of your paper and in a bibliography of sources you used at the end of your paper.

Some useful links about plagiarism:

• MIT Academic Integrity Overview on citing sources and avoiding plagiarism at MIT.
• Avoiding Plagiarism From the MIT Writing and Communication Center.
• Plagiarism: What It is and How to Recognize and Avoid It From Indiana University's Writing Tutorial Services.
• Plagiarism- Overview A resource from Purdue University.
• Next: Citation style guides >>
• Last Updated: Jan 16, 2024 7:02 AM
• URL: https://libguides.mit.edu/citing

• USC Libraries
• Research Guides

Organizing Your Social Sciences Research Paper

• 11. Citing Sources
• Purpose of Guide
• Design Flaws to Avoid
• Independent and Dependent Variables
• Glossary of Research Terms
• Reading Research Effectively
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Applying Critical Thinking
• Choosing a Title
• Making an Outline
• Paragraph Development
• Research Process Video Series
• Executive Summary
• The C.A.R.S. Model
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tiertiary Sources
• Scholarly vs. Popular Publications
• Qualitative Methods
• Quantitative Methods
• Insiderness
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Writing Concisely
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Generative AI and Writing
• USC Libraries Tutorials and Other Guides
• Bibliography

A citation is a formal reference to a published or unpublished source that you consulted and obtained information from while writing your research paper. It refers to a source of information that supports a factual statement, proposition, argument, or assertion or any quoted text obtained from a book, article, web site, or any other type of material . In-text citations are embedded within the body of your paper and use a shorthand notation style that refers to a complete description of the item at the end of the paper. Materials cited at the end of a paper may be listed under the heading References, Sources, Works Cited, or Bibliography. Rules on how to properly cite a source depends on the writing style manual your professor wants you to use for the class [e.g., APA, MLA, Chicago, Turabian, etc.]. Note that some disciplines have their own citation rules [e.g., law].

Citations: Overview. OASIS Writing Center, Walden University; Research and Citation. The Writing Lab and The OWL. Purdue University; Citing Sources. University Writing Center, Texas A&M University.

Reasons for Citing Your Sources

Reasons for Citing Sources in Your Research Paper

English scientist, Sir Isaac Newton, once wrote, "If I have seen further, it is by standing on the shoulders of giants.”* Citations support learning how to "see further" through processes of intellectual discovery, critical thinking, and applying a deliberate method of navigating through the scholarly landscape by tracking how cited works are propagated by scholars over time and the subsequent ways this leads to the devarication of new knowledge.

Listed below are specific reasons why citing sources is an important part of doing good research.

• Shows the reader where to find more information . Citations help readers expand their understanding and knowledge about the issues being investigated. One of the most effective strategies for locating authoritative, relevant sources about a research problem is to review materials cited in studies published by other authors. In this way, the sources you cite help the reader identify where to go to examine the topic in more depth and detail.
• Increases your credibility as an author . Citations to the words, ideas, and arguments of scholars demonstrates that you have conducted a thorough review of the literature and, therefore, you are reporting your research results or proposing recommended courses of action from an informed and critically engaged perspective. Your citations offer evidence that you effectively contemplated, evaluated, and synthesized sources of information in relation to your conceptualization of the research problem.
• Illustrates the non-linear and contested nature of knowledge creation . The sources you cite show the reader how you characterized the dynamics of prior knowledge creation relevant to the research problem and how you managed to effectively identify the contested relationships between problems and solutions proposed among scholars. Citations don't just list materials used in your study, they tell a story about how prior knowledge-making emerged from a constant state of creation, renewal, and transformation.
• Reinforces your arguments . Sources cited in your paper provide the evidence that readers need to determine that you properly addressed the “So What?” question. This refers to whether you considered the relevance and significance of the research problem, its implications applied to creating new knowledge, and its importance for improving practice. In this way, citations draw attention to and support the legitimacy and originality of your own ideas.
• Demonstrates that you "listened" to relevant conversations among scholars before joining in . Your citations tell the reader where you developed an understanding of the debates among scholars. They show how you educated yourself about ongoing conversations taking place within relevant communities of researchers before inserting your own ideas and arguments. In peer-reviewed scholarship, most of these conversations emerge within books, research reports, journal articles, and other cited works.
• Delineates alternative approaches to explaining the research problem . If you disagree with prior research assumptions or you believe that a topic has been understudied or you find that there is a gap in how scholars have understood a problem, your citations serve as the source materials from which to analyze and present an alternative viewpoint or to assert that a different course of action should be pursued. In short, the materials you cite serve as the means by which to argue persuasively against long-standing assumptions propagated in prior studies.
• Helps the reader understand contextual aspects of your research . Cited sources help readers understand the specific circumstances, conditions, and settings of the problem being investigated and, by extension, how your arguments can be fully understood and assessed. Citations place your line of reasoning within a specific contextualized framework based on how others have studied the problem and how you interpreted their findings in support of your overall research objectives.
• Frames the development of concepts and ideas within the literature . No topic in the social and behavioral sciences rests in isolation from research that has taken place in the past. Your citations help the reader understand the growth and transformation of the theoretical assumptions, key concepts, and systematic inquiries that emerged prior to your engagement with the research problem.
• Underscores what sources were most important to you . Your citations represent a set of choices made about what you determined to be the most important sources for understanding the topic. They not only list what you discovered, but why it matters and how the materials you chose to cite fit within the broader context of your research design and arguments. As part of an overall assessment of the study’s validity and reliability , the choices you make also helps the reader determine what research may have been excluded.
• Provides evidence of interdisciplinary thinking . An important principle of good research is to extend your review of the literature beyond the predominant disciplinary space where scholars have examined a topic. Citations provide evidence that you have integrated epistemological arguments, observations, and/or the methodological strategies from other disciplines into your paper, thereby demonstrating that you understand the complex, interconnected nature of contemporary research problems.
• Supports critical thinking and independent learning . Evaluating the authenticity, reliability, validity, and originality of prior research is an act of interpretation and introspective reasoning applied to assessing whether a source of information will contribute to understanding the problem in ways that are persuasive and align with your overall research objectives. Reviewing and citing prior studies represents a deliberate act of critically scrutinizing each source as part of your overall assessment of how scholars have confronted the research problem.
• Honors the achievements of others . As Susan Blum recently noted,** citations not only identify sources used, they acknowledge the achievements of scholars within the larger network of research about the topic. Citing sources is a normative act of professionalism within academe and a way to highlight and recognize the work of scholars who likely do not obtain any tangible benefits or monetary value from their research endeavors.

*Vernon. Jamie L. "On the Shoulder of Giants." American Scientist 105 (July-August 2017): 194.

**Blum, Susan D. "In Defense of the Morality of Citation.” Inside Higher Ed , January 29, 2024.

Aksnes, Dag W., Liv Langfeldt, and Paul Wouters. "Citations, Citation Indicators, and Research Quality: An Overview of Basic Concepts and Theories." Sage Open 9 (January-March 2019): https://doi.org/10.1177/2158244019829575; Blum, Susan Debra. My Word!: Plagiarism and College Culture . Ithaca, NY: Cornell University Press, 2009; Bretag, Tracey., editor. Handbook of Academic Integrity . Singapore: Springer Singapore, 2020; Ballenger, Bruce P. The Curious Researcher: A Guide to Writing Research Papers . 7th edition. Boston, MA: Pearson, 2012; D'Angelo, Barbara J. "Using Source Analysis to Promote Critical Thinking." Research Strategies 18 (Winter 2001): 303-309; Mauer, Barry and John Venecek. “Scholarship as Conversation.” Strategies for Conducting Literary Research, University of Central Florida, 2021; Why Cite? Poorvu Center for Teaching and Learning, Yale University; Citing Information. The Writing Center. University of North Carolina; Harvard Guide to Using Sources. Harvard College Writing Program. Harvard University; Newton, Philip. "Academic Integrity: A Quantitative Study of Confidence and Understanding in Students at the Start of Their Higher Education."  Assessment and Evaluation in Higher Education 41 (2016): 482-497; Referencing More Effectively. Academic Skills Centre. University of Canberra; Using Sources. Yale College Writing Center. Yale University; Vosburgh, Richard M. "Closing the Academic-practitioner Gap: Research Must Answer the “SO WHAT” Question." H uman Resource Management Review 32 (March 2022): 100633; When and Why to Cite Sources. Information Literacy Playlists, SUNY, Albany Libraries.

Structure and Writing Style

Referencing your sources means systematically showing what information or ideas you acquired from another author’s work, and identifying where that information come from . You must cite research in order to do research, but at the same time, you must delineate what are your original thoughts and ideas and what are the thoughts and ideas of others. Citations help achieve this. Procedures used to cite sources vary among different fields of study. If not outlined in your course syllabus or writing assignment, always speak with your professor about what writing style for citing sources should be used for the class because it is important to fully understand the citation style to be used in your paper, and to apply it consistently. If your professor defers and tells you to "choose whatever you want, just be consistent," then choose the citation style you are most familiar with or that is appropriate to your major [e.g., use Chicago style if its a history class; use APA if its an education course; use MLA if it is literature or a general writing course].

GENERAL GUIDELINES

1. Are there any reasons I should avoid referencing other people's work? No. If placed in the proper context, r eferencing other people's research is never an indication that your work is substandard or lacks originality. In fact, the opposite is true. If you write your paper without adequate references to previous studies, you are signaling to the reader that you are not familiar with the literature on the topic, thereby, undermining the validity of your study and your credibility as a researcher. Including references in academic writing is one of the most important ways to demonstrate your knowledge and understanding of how the research problem has been addressed. It is the intellectual packaging around which you present your thoughts and ideas to the reader.

2. What should I do if I find out that my great idea has already been studied by another researcher? It can be frustrating to come up with what you believe is a great topic only to find that it's already been thoroughly studied. However, do not become frustrated by this. You can acknowledge the prior research by writing in the text of your paper [see also Smith, 2002], then citing the complete source in your list of references. Use the discovery of prior studies as an opportunity to demonstrate the significance of the problem being investigated and, if applicable, as a means of delineating your analysis from those of others [e.g., the prior study is ten years old and doesn't take into account new variables]. Strategies for responding to prior research can include: stating how your study updates previous understandings about the topic, offering a new or different perspective, applying a different or innovative method of data gathering, and/or describing a new set of insights, guidelines, recommendations, best practices, or working solutions.

3. What should I do if I want to use an adapted version of someone else's work? You still must cite the original work. For example, maybe you are using a table of statistics from a journal article published in 1996 by author Smith, but you have altered or added new data to it. Reference the revised chart, such as, [adapted from Smith, 1996], then cite the complete source in your list of references. You can also use other terms in order to specify the exact relationship between the original source and the version you have presented, such as, "based on data from Smith [1996]...," or "summarized from Smith [1996]...." Citing the original source helps the reader locate where the information was first presented and under what context it was used as well as to evaluate how effectively you applied it to your own research.

4. What should I do if several authors have published very similar information or ideas? You can indicate that the idea or information can be found in the works of others by stating something similar to the following example: "Though many scholars have applied rational choice theory to understanding economic relations among nations [Smith, 1989; Jones, 1991; Johnson, 1994; Anderson, 2003], little attention has been given to applying the theory to examining the influence of non-governmental organizations in a globalized economy." If you only reference one author or only the most recent study, then your readers may assume that only one author has published on this topic, or more likely, they will conclude that you have not conducted a thorough literature review. Referencing all relevant authors of prior studies gives your readers a clear idea of the breadth of analysis you conducted in preparing to study the research problem. If there has been a significant number of prior studies on the topic, describe the most comprehensive and recent works because they will presumably discuss and reference the older studies. However, note in your review of the literature that there has been significant scholarship devoted to the topic so the reader knows that you are aware of the numerous prior studies.

5. What if I find exactly what I want to say in the writing of another researcher? In the social sciences, the rationale in duplicating prior research is generally governed by the passage of time, changing circumstances or conditions, or the emergence of variables that necessitate a new investigation . If someone else has recently conducted a thorough investigation of precisely the same research problem that you intend to study, then you likely will have to revise your topic, or at the very least, review this literature to identify something new to say about the problem. However, if it is someone else's particularly succinct expression, but it fits perfectly with what you are trying to say, then you can quote from the author directly, referencing the source. Identifying an author who has made the exact same point that you want to make can be an opportunity to add legitimacy to, as well as reinforce the significance of, the research problem you are investigating. The key is to build on that idea in new and innovative ways. If you are not sure how to do this, consult with a librarian .

6. Should I cite a source even if it was published long ago? Any source used in writing your paper should be cited, regardless of when it was written. However, in building a case for understanding prior research about your topic, it is generally true that you should focus on citing more recently published studies because they presumably have built upon the research of older studies. When referencing prior studies, use the research problem as your guide when considering what to cite. If a study from forty years ago investigated the same topic, it probably should be examined and considered in your list of references because the research may have been foundational or groundbreaking at the time, even if its findings are no longer relevant to current conditions or reflect current thinking [one way to determine if a study is foundational or groundbreaking is to examine how often it has been cited in recent studies using the "Cited by" feature of Google Scholar ]. However, if an older study only relates to the research problem tangentially or it has not been cited in recent studies, then it may be more appropriate to list it under further readings .

7. Can I cite unusual and non-scholarly sources in my research paper? The majority of the citations in a research paper should be to scholarly [a.k.a., academic; peer-reviewed] studies that rely on an objective and logical analysis of the research problem based on empirical evidence that reliably supports your arguments. However, any type of source can be considered valid if it brings relevant understanding and clarity to the topic. This can include, for example, non-textual elements such as photographs, maps, or illustrations. A source can include materials from special or archival collections, such as, personal papers, manuscripts, business memorandums, the official records of an organization, or digitized collections. Citations can also be to unusual items, such as, an audio recording, a transcript from a television show, a unique set of data, or a social media post. The challenge is knowing how to properly cite unusual and non-scholarly sources because they often do not fit within standard citation rules like books or journal articles. Given this, consult with a librarian if you are unsure how to cite a source.

NOTE:   In any academic writing, you are required to identify which ideas, facts, thoughts, concepts, or declarative statements are yours and which are derived from the research of others. The only exception to this rule is information that is considered to be a commonly known fact [e.g., "George Washington was the first president of the United States"] or a statement that is self-evident [e.g., "Australia is a country in the Global South"]. Appreciate, however, that any "commonly known fact" or self-evidencing statement is culturally constructed and shaped by specific social and aesthetical biases . If you have any doubt about whether or not a fact is considered to be widely understood knowledge, provide a supporting citation, or, ask your professor for clarification about whether the statement should be cited.

Ballenger, Bruce P. The Curious Researcher: A Guide to Writing Research Papers . 7th edition. Boston, MA: Pearson, 2012; Blum, Susan Debra. My Word!: Plagiarism and College Culture . Ithaca, NY: Cornell University Press, 2009; Bretag, Tracey., editor. Handbook of Academic Integrity . Singapore: Springer Singapore, 2020; Carlock, Janine. Developing Information Literacy Skills: A Guide to Finding, Evaluating, and Citing Sources . Ann Arbor, MI: University of Michigan Press, 2020; Harvard Guide to Using Sources. Harvard College Writing Program. Harvard University; How to Cite Other Sources in Your Paper. The Structure, Format, Content, and Style of a Journal-Style Scientific Paper. Department of Biology. Bates College; Lunsford, Andrea A. and Robert Connors; The St. Martin's Handbook . New York: St. Martin's Press, 1989; Mills, Elizabeth Shown. Evidence Explained: Citing History Sources from Artifacts to Cyberspace . 3rd edition. Baltimore, MD: Genealogical Publishing Company, 2015; Research and Citation Resources. The Writing Lab and The OWL. Purdue University; Writing Tutorial Services, Center for Innovative Teaching and Learning. Indiana University; Why Cite? Poorvu Center for Teaching and Learning, Yale Univeraity.

Other Citation Research Guides

The following USC Libraries research guide can help you properly cite sources in your research paper:

• Citation Guide

The following USC Libraries research guide offers basic information on using images and media in research:

Listed below are particularly well-done and comprehensive websites that provide specific examples of how to cite sources under different style guidelines.

• Purdue University Online Writing Lab
• Southern Cross University Harvard Referencing Style
• University of Wisconsin Writing Center

This is a useful guide concerning how to properly cite images in your research paper.

• Colgate Visual Resources Library, Citing Images

This guide provides good information on the act of citation analysis, whereby you count the number of times a published work is cited by other works in order to measure the impact of a publication or author.

Measuring Your Impact: Impact Factor, Citation Analysis, and other Metrics: Citation Analysis [Sandy De Groote, University of Illinois, Chicago]

Automatic Citation Generators

The links below lead to systems where you can type in your information and have a citation compiled for you. Note that these systems are not foolproof so it is important that you verify that the citation is correct and check your spelling, capitalization, etc. However, they can be useful in creating basic types of citations, particularly for online sources.

• BibMe -- APA, MLA, Chicago, and Turabian styles
• DocsCite -- for citing government publications in APA or MLA formats
• EasyBib -- APA, MLA, and Chicago styles
• Son of Citation Machine -- APA, MLA, Chicago, and Turabian styles

NOTE:   Many companies that create the research databases the USC Libraries subscribe to, such as ProQuest , include built-in citation generators that help take the guesswork out of how to properly cite a work. When available, you should always utilize these features because they not only generate a citation to the source [e.g., a journal article], but include information about where you accessed the source [e.g., the database].

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When to Cite a Source in a Paper

And What Is Common Knowledge?

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• Writing Research Papers
• Writing Essays
• English Grammar
• M.Ed., Education Administration, University of Georgia
• B.A., History, Armstrong State University

"Write an essay and back it up with facts."

How many times have you heard a teacher or professor say this? But many students might wonder what exactly counts as a fact, and what doesn't. That means they don't know when it is proper to cite a source, and when it's OK not to use a citation.

Dictionary.com states that a fact is:

• Something demonstrated to exist or known to have existed.

"Demonstrated" is a hint here. What the teacher means when she/he tells you to use facts is that you need to back up your claims with some evidence that supports your claims (sources). It's one trick that teachers use to make sure you actually use some references when you write a paper, instead of simply offering a list of your opinions.

This may sound easy, but it's actually tough sometimes to know when you need to back up a statement with evidence and when it is fine to leave a statement unsupported.

When to Cite a Source

You should use evidence ( citations ) any time you make a claim that is not based on a well-known fact or common knowledge. Here's a list of situations when your teacher would expect a citation:

• You make a specific claim that could be challenged--like London is the foggiest city in the world. 
• You quote somebody.
• You make a specific claim that is not common knowledge like the Indian Ocean is the youngest of the world's major oceans.
• You paraphrase information from a source (give the meaning but change the wording).
• Offer an authoritative (expert) opinion--like "germs cause pneumonia."
• You got an idea from somebody else, even through email or conversation.

Although there may be interesting facts that you have believed or know for many years, you will be expected to provide proof of those facts when you're writing a paper for school.

Examples of Claims You Should Support

• Hot water can freeze faster than cold water.
• Poodles are friendlier than Dalmatians.
• American Chestnut trees are nearly extinct.
• Eating while driving is more dangerous than talking on the cell phone while driving.
• Thomas Edison invented a vote counter.

When You Don't Need to Cite a Source

So how do you know when you do not need to cite a source? Common knowledge is basically a fact that practically everyone knows, like the fact that George Washington was a U.S. president.

More Examples of Common Knowledge or Well-Known Facts

• Bears hibernate in the winter.
• Fresh water freezes at 32 degrees F.
• Many trees shed their leaves in the fall.
• Some trees do not shed their leaves in the fall.
• Bears hibernate.

A well-known fact is something that many people know, but it is also something that a reader could look up easily if he/she didn't know.

• It's best to plant flowers in the early spring.
• Holland is famous for its tulips.
• Canada has a multilingual population.

If you're not really certain about something being common knowledge, you could give it the little sister test. If you have a younger sibling, ask him or her the subject you're pondering. If you get an answer, it could be common knowledge!

A Good Rule of Thumb

A good rule of thumb for any writer is to go ahead and use a citation when you're not certain whether or not the citation is necessary. The only risk in doing this is littering your paper with unnecessary citations that will drive your teacher crazy. Too many citations will give your teacher the impression that you are attempting to stretch your paper to a certain word count!

Simply trust your own best judgment and be honest with yourself. You'll get the hang of it soon!

• 50 Argumentative Essay Topics
• Turabian Style Guide With Examples
• Tips for Typing an Academic Paper on a Computer
• What Is Plagiarism?
• What Is a Citation?
• How Long Should Your Web Page Be?
• MLA Style Parenthetical Citations
• Writing a History Book Review
• Finding Trustworthy Sources
• MLA Bibliography or Works Cited
• How to Develop a Research Paper Timeline
• 4 Tips for Using Textual Evidence for Short Stories
• Ethos, Logos, Pathos for Persuasion
• What Is a Bibliography?
• How to Cite Genealogy Sources
• APA In-Text Citations

University Library

Start your research.

• Research Process
• Find Background Info
• Find Sources through the Library
• Evaluate Your Info
• Cite Your Sources
• Evaluate, Write & Cite

• is the right thing to do  to give credit to those who had the idea
• shows that you have read and understand  what experts have had to say about your topic
• helps people find the sources  that you used in case they want to read more about the topic
• provides   evidence  for your arguments
• is professional and  standard practice   for students and scholars

What is a Citation?

A citation identifies for the reader the original source for an idea, information, or image that is referred to in a work.

• In the body of a paper, the  in-text citation  acknowledges the source of information used.
• At the end of a paper, the citations are compiled on a  References  or  Works Cited  list. A basic citation includes the author, title, and publication information of the source. 

From:  Lemieux  Library,  University  of Seattle 

Why Should You Cite?

Quoting Are you quoting two or more consecutive words from a source? Then the original source should be cited and the words or phrase placed in quotes. 

Paraphrasing If an idea or information comes from another source,  even if you put it in your own words , you still need to credit the source.  General vs. Unfamiliar Knowledge You do not need to cite material which is accepted common knowledge. If in doubt whether your information is common knowledge or not, cite it. Formats We usually think of books and articles. However, if you use material from web sites, films, music, graphs, tables, etc. you'll also need to cite these as well.

Plagiarism is presenting the words or ideas of someone else as your own without proper acknowledgment of the source. When you work on a research paper and use supporting material from works by others, it's okay to quote people and use their ideas, but you do need to correctly credit them. Even when you summarize or paraphrase information found in books, articles, or Web pages, you must acknowledge the original author.

Citation Style Help

Helpful links:

• MLA ,  Works Cited : A Quick Guide (a template of core elements)
• CSE  (Council of Science Editors)

For additional writing resources specific to styles listed here visit the  Purdue OWL Writing Lab

Citation and Bibliography Resources

• How to Write an Annotated Bibliography
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Creative Commons Attribution 3.0 License except where otherwise noted.

Land Acknowledgement

The land on which we gather is the unceded territory of the Awaswas-speaking Uypi Tribe. The Amah Mutsun Tribal Band, comprised of the descendants of indigenous people taken to missions Santa Cruz and San Juan Bautista during Spanish colonization of the Central Coast, is today working hard to restore traditional stewardship practices on these lands and heal from historical trauma.

The land acknowledgement used at UC Santa Cruz was developed in partnership with the Amah Mutsun Tribal Band Chairman and the Amah Mutsun Relearning Program at the UCSC Arboretum .

• MJC Library & Learning Center
• Research Guides

Format Your Paper & Cite Your Sources

Citing sources, why does citing sources matter, what do you cite, tips for citing sources.

• Avoid Plagiarism
• MLA Style (8th/9th ed.)
• APA Style, 7th Edition
• Chicago Style
• Harvard Style
• Other Styles
• Annotated Bibliographies
• How to Create an Attribution

When you write a research paper, you use information and facts from a variety of resources to support your own ideas or to help you develop new ones. Books, articles, videos, interviews, and Web sites are some examples of sources you might use.

Citing these sources of information in your work is essential because:

• It gives credit to the author of the original work who provided you with the information or idea
• It allows your audience to identify and find the source material in order to learn more about your topic
• It gives your paper more credibility because it shows you're supporting your arguments with high-quality source. It also helps earn your readers' trust because you're telling your readers the source of your facts so that they can confirm them for themselves
• It helps you avoid plagiarism

Watch this short video from The Learning Portal to learn why you cite and when you cite. Watch, Learn, and Enjoy!

"Why You Need to Cite Sources" by The Learning Portal is licensed under CC BY-NC-SA 4.0

Cite all outside sources you use in your research paper! Citing is required for sources you:

Quote  word-for-word,

Paraphrase  (rewrite using your own words), and

Summarize (rewrite the main concept or idea in your own words) .  

How Citation Style Affects Your Paper:

No matter which citation style you use, you need to cite your sources within the body of your paper where you incorporate your outside sources (in-text citations) and in your cumulative list of sources at the end of your paper (Works Cited, References, or Bibliography)

Collect the Information You Need

It's important to make sure you collect all the information you need to cite a source as you gather your information so that you won't need to look it up again, so:

• Take clear, accurate notes about where you found specific ideas
• Write down the complete citation information for each book, article, etc. you use as you go along
• Use quotation marks when directly stating another person's words
• Always credit original authors for their information and ideas

Keep Track of Information About Your Sources

As you explore your topic, you'll discover and read information from many different sources. With each new source, you'll need to decide if you want to use it. To help you make this decision, you'll ask yourself questions about the source like:

• Who  is the author of this source?
• What  is the title of the source?
• How  was the source published?
• Where  did I find this source?
• When  was the source published?

Each of these elements (author, title, publisher, location, publication date) will become part of your citation. As you work, you'll want to keep track of each of these elements so that creating your citations will be easier.

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APA Citations 7th Edition

• Why, When, and How to Cite
• General Tips & Sample Reference List
• Cite Books, Edited Book Chapters, and Entries From Reference Books
• Cite Journal, Magazine, Newspaper, and Blog Articles
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• Cite Social Media and Webpages; and Guidance on Websites
• In-Text Citations
• Additional Help

Why to Cite

There are many reasons to cite your sources:

• to give credit to authors or artists whose work you have used
• to allow people who are reviewing your work to check your sources
• to show readers how you came up with your arguments or ideas
• to provide scholars with other sources for their research
• to avoid plagiarism

For more information about the dangers of plagiarism see the APA Blog .

For a quick overview of why  and when  to cite, view this short video, Cite a Source: How and Why You Should Do It .

Test your understanding of plagiarism by taking this short Plagiarism Quiz .

What you don't know CAN hurt you!

When to Cite

Cite a source when:

• you copy information exactly from it; t his includes primary sources, such as when you have interviewed someone or are referring to a work of art or image that you are referencing
• you paraphrase, summarize or use your own words to describe ideas from a work
• you cite statistics, data or other numerical information that was compiled by someone other than yourself.

​ NOTE: The exception to the rule is that you do not have to cite a source when you are using what is considered "common knowledge," such as a date in history, basic biographical facts about a prominent person, or the dates and circumstances of major historical events (e.g. there are 12 months in a year, the planets revolve around the sun, the American Civil War began on April 12, 1861, etc.). If the facts are in dispute, it is best to cite sources.

How to Cite

The essential components of APA citation style are the reference list and related in-text citations. These two components work together to allow readers to find the exact sources used by the writer, as well as where in the paper these sources were used.

The reference list is the master list of all sources used, and is located after the body of the paper. Each source has its own entry on the list and is written in a highly stylized format. The four basic elements of a reference are:

Author. (Date). Title. Source.

For example, here is a citation for an article from a magazine which contains the four basic elements along with additional elements needed to accurately describe a magazine article:

Chesney, R., & Citron, D. (2019, January/February). Deepfakes and the new disinformation war: The coming age of post-truth geopolitics. Foreign Affairs , 98 (1), 147–155.

When sources are used in the body of the paper, in-text citations are the link back to the exact entry for the source appearing on the reference list. For example, when the above source is quoted in the body of the paper it includes an embedded in-text citation:

Chesney (2019) speculates that "as deepfake technology develops and spreads, the current disinformation wars may soon look like the propaganda equivalent of the era of swords and shields."

Kinds of Sources

How to cite a source in the reference list is determined by the kind of source it is. APA citation style organizes sources into reference groups , then categories , and then types . The essential groups /categories / types covered in this guide are:

The one remaining group APA recognizes, "data sets, software, and tests," is not covered in this guide.

For more in-depth information on APA groups / categories / types, with examples, visit this APA Style Blog page .

NOTE: When selecting a group / category / type for a source, what group / category / type a source falls into is of more importance than how it happened to be accessed. For example, if you wanted to cite an article from a journal, when selecting a category/group/type the deciding factor would be that it was an article from a journal, not that you read it in print, or in a library research database, or on a website.  

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• Referencing

A Quick Guide to Referencing | Cite Your Sources Correctly

Referencing means acknowledging the sources you have used in your writing. Including references helps you support your claims and ensures that you avoid plagiarism .

There are many referencing styles, but they usually consist of two things:

• A citation wherever you refer to a source in your text.
• A reference list or bibliography at the end listing full details of all your sources.

The most common method of referencing in UK universities is Harvard style , which uses author-date citations in the text. Our free Harvard Reference Generator automatically creates accurate references in this style.

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Table of contents

Referencing styles, citing your sources with in-text citations, creating your reference list or bibliography, harvard referencing examples, frequently asked questions about referencing.

Each referencing style has different rules for presenting source information. For in-text citations, some use footnotes or endnotes , while others include the author’s surname and date of publication in brackets in the text.

The reference list or bibliography is presented differently in each style, with different rules for things like capitalisation, italics, and quotation marks in references.

Your university will usually tell you which referencing style to use; they may even have their own unique style. Always follow your university’s guidelines, and ask your tutor if you are unsure. The most common styles are summarised below.

Harvard referencing, the most commonly used style at UK universities, uses author–date in-text citations corresponding to an alphabetical bibliography or reference list at the end.

Harvard Referencing Guide

Vancouver referencing, used in biomedicine and other sciences, uses reference numbers in the text corresponding to a numbered reference list at the end.

Vancouver Referencing Guide

APA referencing, used in the social and behavioural sciences, uses author–date in-text citations corresponding to an alphabetical reference list at the end.

APA Referencing Guide APA Reference Generator

MHRA referencing, used in the humanities, uses footnotes in the text with source information, in addition to an alphabetised bibliography at the end.

MHRA Referencing Guide

OSCOLA referencing, used in law, uses footnotes in the text with source information, and an alphabetical bibliography at the end in longer texts.

OSCOLA Referencing Guide

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In-text citations should be used whenever you quote, paraphrase, or refer to information from a source (e.g. a book, article, image, website, or video).

Quoting and paraphrasing

Quoting is when you directly copy some text from a source and enclose it in quotation marks to indicate that it is not your own writing.

Paraphrasing is when you rephrase the original source into your own words. In this case, you don’t use quotation marks, but you still need to include a citation.

In most referencing styles, page numbers are included when you’re quoting or paraphrasing a particular passage. If you are referring to the text as a whole, no page number is needed.

In-text citations

In-text citations are quick references to your sources. In Harvard referencing, you use the author’s surname and the date of publication in brackets.

Up to three authors are included in a Harvard in-text citation. If the source has more than three authors, include the first author followed by ‘ et al. ‘

The point of these citations is to direct your reader to the alphabetised reference list, where you give full information about each source. For example, to find the source cited above, the reader would look under ‘J’ in your reference list to find the title and publication details of the source.

Placement of in-text citations

In-text citations should be placed directly after the quotation or information they refer to, usually before a comma or full stop. If a sentence is supported by multiple sources, you can combine them in one set of brackets, separated by a semicolon.

If you mention the author’s name in the text already, you don’t include it in the citation, and you can place the citation immediately after the name.

• Another researcher warns that the results of this method are ‘inconsistent’ (Singh, 2018, p. 13) .
• Previous research has frequently illustrated the pitfalls of this method (Singh, 2018; Jones, 2016) .
• Singh (2018, p. 13) warns that the results of this method are ‘inconsistent’.

The terms ‘bibliography’ and ‘reference list’ are sometimes used interchangeably. Both refer to a list that contains full information on all the sources cited in your text. Sometimes ‘bibliography’ is used to mean a more extensive list, also containing sources that you consulted but did not cite in the text.

A reference list or bibliography is usually mandatory, since in-text citations typically don’t provide full source information. For styles that already include full source information in footnotes (e.g. OSCOLA and Chicago Style ), the bibliography is optional, although your university may still require you to include one.

Format of the reference list

Reference lists are usually alphabetised by authors’ last names. Each entry in the list appears on a new line, and a hanging indent is applied if an entry extends onto multiple lines.

Different source information is included for different source types. Each style provides detailed guidelines for exactly what information should be included and how it should be presented.

Below are some examples of reference list entries for common source types in Harvard style.

• Chapter of a book
• Journal article

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Your university should tell you which referencing style to follow. If you’re unsure, check with a supervisor. Commonly used styles include:

• Harvard referencing , the most commonly used style in UK universities.
• MHRA , used in humanities subjects.
• APA , used in the social sciences.
• Vancouver , used in biomedicine.
• OSCOLA , used in law.

Your university may have its own referencing style guide.

If you are allowed to choose which style to follow, we recommend Harvard referencing, as it is a straightforward and widely used style.

References should be included in your text whenever you use words, ideas, or information from a source. A source can be anything from a book or journal article to a website or YouTube video.

If you don’t acknowledge your sources, you can get in trouble for plagiarism .

To avoid plagiarism , always include a reference when you use words, ideas or information from a source. This shows that you are not trying to pass the work of others off as your own.

You must also properly quote or paraphrase the source. If you’re not sure whether you’ve done this correctly, you can use the Scribbr Plagiarism Checker to find and correct any mistakes.

Harvard referencing uses an author–date system. Sources are cited by the author’s last name and the publication year in brackets. Each Harvard in-text citation corresponds to an entry in the alphabetised reference list at the end of the paper.

Vancouver referencing uses a numerical system. Sources are cited by a number in parentheses or superscript. Each number corresponds to a full reference at the end of the paper.

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Citing Sources

• What Information Should be Cited and Why?
• Intentional & Unintentional Plagiarism
• Tips for Avoiding Plagiarism
• Resources & Help
• APA Style -- 7th edition (2019)
• In-text Citations
• Formatting your Paper
• Works Cited List
• Websites & Web Materials
• Chicago Style

• What are the library hours?
• How do I take materials out of the libraries? To check out materials, go to the front desk (check out desk) at the Library. You'll need your Holy Family ID card.
• How do I access the databases to find articles from off campus? Sign-In using the same log-in as your Canvas account.
• What do I do if full text is not available in a database? Our databases include abstracts (summaries) and selected full text of articles. If the full-text article is not available in one database, it may be available in another. Search the Publication Finder by journal title to see which database includes the full text.
• How can I get items from another library when Holy Family does not have what I need? If we don't have the item that you need in our collection, we can request it for you from another library. Fill out an Interlibrary Loan request form.
• How do I cite in APA, MLA or Chicago style? See our citation guides for examples of citation in various citation styles.
• How does faculty request library instruction for a class?
• If a professor says they have a book on reserve in the Library, what does that mean? Instructors can place items on reserve in the Library for their class using a Library service called "Course Reserve." Click the link for more information regarding this service.

Why Do We Cite Our Research?

Sources of information are cited in order to give the original authors/creators proper credit for their work and to document where an author heard or read the fact or idea that has been incorporated into a new work. The purpose of citations is to let the reader know where you obtained information so sources can easily be located and consulted.

Because knowledge is a cumulative process built on the research and writing of other researchers, your instructor needs to see the quality of the sources you used and how you developed your ideas.

To get started and to see examples, select the citation style from the dropdown menu on the left.

What Information Should Be Cited and Why?

In general, you must document sources when you provide information that you ordinarily would not have known before conducting your research, and when you provide information that it cannot be assumed the reader knows. You must cite a reference when you:

• Discuss, summarize, or paraphrase the ideas of an author
• Provide a direct quotation
• Use statistical or other data
• Use images, graphics, videos, and other media

While you are doing research and locating sources, be sure to document materials thoroughly, noting the author, title, publisher, place of publication, date, and page numbers of all sources used. For electronic materials, you should also note the DOI number (Digital Object Identifier) if available. Note the URL of any website you consult; depending on the source, you may need it for reference.

APA style no longer requires a database name for most references; MLA style still requires it as part of your citation. In either case, make a note of it in case you need to retrieve it at a later date.

Common Knowledge

Things that are common knowledge do not require citation. For example:

• Social networking sites such as Facebook allow people to communicate easily regardless of their location. (does not require citation)
• The Japanese navy attacked Pearl Harbor on December 7, 1941. (does not require citation)

However, if someone draws an original conclusion from a common fact, then you must cite the source:

• The ability to share real-time news and video with the world via social networking sites has emboldened student movements in countries where there is very little freedom of the press. (requires citation)
• Japan's failure to sink any U.S. aircraft carriers in the otherwise devastating attack on Pearl Harbor assured Japan's eventual defeat. (requires citation)

Also, common sayings or proverbs need not be cited:

• "The early bird gets the worm." (common expression with no distinct origin)

Below is a famous saying you might recognize, but it's actually from a poem by Sir Walter Scott. If you read this in a book, of course, you would cite the book. If you already knew this expression, you should still give Sir Walter Scott credit for it because it has a distinct and identifiable origin.

• "Oh, what a tangled web we weave when first we practice to deceive."

Getting started

We understand that citing your sources can be a little confusing, but it doesn't have to be overwhelming. Before you start, ask yourself these questions:

1. What type of source am I trying to cite?

• Journal article? Book? Webpage?

2. Where did I retrieve that source?

• Library database? Website? Was it a print source?

3. What citation style am I supposed to use for my assignment?

Once you've answered these questions, select the most appropriate option from either the  APA  or  MLA  dropdown menu.

To request a one-on-one consultation with a librarian to begin research on a paper, find sources, or review the APA/MLA formatting of their paper and/or references please make an appointment with us through our online web form . We offer both online and in-person options

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How to Cite a Research Paper

Last Updated: March 29, 2024 Fact Checked

This article was reviewed by Gerald Posner and by wikiHow staff writer, Jennifer Mueller, JD . Gerald Posner is an Author & Journalist based in Miami, Florida. With over 35 years of experience, he specializes in investigative journalism, nonfiction books, and editorials. He holds a law degree from UC College of the Law, San Francisco, and a BA in Political Science from the University of California-Berkeley. He’s the author of thirteen books, including several New York Times bestsellers, the winner of the Florida Book Award for General Nonfiction, and has been a finalist for the Pulitzer Prize in History. He was also shortlisted for the Best Business Book of 2020 by the Society for Advancing Business Editing and Writing. There are 8 references cited in this article, which can be found at the bottom of the page. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. This article has been viewed 415,806 times.

When writing a paper for a research project, you may need to cite a research paper you used as a reference. The basic information included in your citation will be the same across all styles. However, the format in which that information is presented is somewhat different depending on whether you're using American Psychological Association (APA), Modern Language Association (MLA), Chicago, or American Medical Association (AMA) style.

Referencing a Research Paper

• In APA style, cite the paper: Last Name, First Initial. (Year). Title. Publisher.
• In Chicago style, cite the paper: Last Name, First Name. “Title.” Publisher, Year.
• In MLA style, cite the paper: Last Name, First Name. “Title.” Publisher. Year.

Citation Help

• For example: "Kringle, K., & Frost, J."

• For example: "Kringle, K., & Frost, J. (2012)."
• If the date, or any other information, are not available, use the guide at https://blog.apastyle.org/apastyle/2012/05/missing-pieces.html .

• For example: "Kringle, K., & Frost, J. (2012). Red noses, warm hearts: The glowing phenomenon among North Pole reindeer."
• If you found the research paper in a database maintained by a university, corporation, or other organization, include any index number assigned to the paper in parentheses after the title. For example: "Kringle, K., & Frost, J. (2012). Red noses, warm hearts: The glowing phenomenon among North Pole reindeer. (Report No. 1234)."

• For example: "Kringle, K., & Frost, J. (2012). Red noses, warm hearts: The glowing phenomenon among North Pole reindeer. (Report No. 1234). Retrieved from Alaska University Library Archives, December 24, 2017."

• For example: "(Kringle & Frost, 2012)."
• If there was no date on the research paper, use the abbreviation n.d. : "(Kringle & Frost, n.d.)."

• For example: "Kringle, Kris, and Jack Frost."

• For example: "Kringle, Kris, and Jack Frost. "Red Noses, Warm Hearts: The Glowing Phenomenon among North Pole Reindeer." Master's thesis."

• For example: "Kringle, Kris, and Jack Frost. "Red Noses, Warm Hearts: The Glowing Phenomenon among North Pole Reindeer." Master's thesis, Alaska University, 2012."

• For example: "Kringle, Kris, and Jack Frost. "Red Noses, Warm Hearts: The Glowing Phenomenon among North Pole Reindeer." Master's thesis, Alaska University, 2012. Accessed at https://www.northpolemedical.com/raising_rudolf."

• Footnotes are essentially the same as the full citation, although the first and last names of the authors aren't inverted.
• For parenthetical citations, Chicago uses the Author-Date format. For example: "(Kringle and Frost 2012)."

• For example: "Kringle, Kris, and Frost, Jack."

• For example: "Kringle, Kris, and Frost, Jack. "Red Noses, Warm Hearts: The Glowing Phenomenon Among North Pole Reindeer.""

• For example, suppose you found the paper in a collection of paper housed in university archives. Your citation might be: "Kringle, Kris, and Frost, Jack. "Red Noses, Warm Hearts: The Glowing Phenomenon Among North Pole Reindeer." Master's Theses 2000-2010. University of Alaska Library Archives. Accessed December 24, 2017."

• For example: "(Kringle & Frost, p. 33)."

• For example: "Kringle K, Frost J."

• For example: "Kringle K, Frost J. Red noses, warm hearts: The glowing phenomenon among North Pole reindeer."

• For example: "Kringle K, Frost J. Red noses, warm hearts: The glowing phenomenon among North Pole reindeer. Nat Med. 2012; 18(9): 1429-1433."

• For example, if you're citing a paper presented at a conference, you'd write: "Kringle K, Frost J. Red noses, warm hearts: The glowing phenomenon among North Pole reindeer. Oral presentation at Arctic Health Association Annual Summit; December, 2017; Nome, Alaska."
• To cite a paper you read online, you'd write: "Kringle K, Frost J. Red noses, warm hearts: The glowing phenomenon among North Pole reindeer. https://www.northpolemedical.com/raising_rudolf"

• For example: "According to Kringle and Frost, these red noses indicate a subspecies of reindeer native to Alaska and Canada that have migrated to the North Pole and mingled with North Pole reindeer. 1 "

Community Q&A

• If you used a manual as a source in your research paper, you'll need to learn how to cite the manual also. Thanks Helpful 0 Not Helpful 0
• If you use any figures in your research paper, you'll also need to know the proper way to cite them in MLA, APA, AMA, or Chicago. Thanks Helpful 0 Not Helpful 0

You Might Also Like

• ↑ https://askus.library.wwu.edu/faq/116659
• ↑ https://guides.libraries.psu.edu/apaquickguide/intext
• ↑ https://owl.purdue.edu/owl/research_and_citation/chicago_manual_17th_edition/cmos_formatting_and_style_guide/general_format.html
• ↑ https://libanswers.snhu.edu/faq/48009
• ↑ https://www.chicagomanualofstyle.org/tools_citationguide/citation-guide-2.html
• ↑ https://owl.purdue.edu/owl/research_and_citation/mla_style/mla_formatting_and_style_guide/mla_in_text_citations_the_basics.html
• ↑ https://morningside.libguides.com/MLA8/location
• ↑ https://owl.purdue.edu/owl/research_and_citation/ama_style/index.html

About This Article

To cite a paper APA style, start with the author's last name and first initial, and the year of publication. Then, list the title of the paper, where you found it, and the date that you accessed it. In a paper, use a parenthetical reference with the last name of the author and the publication year. For an MLA citation, list the author's last name and then first name and the title of the paper in quotations. Include where you accessed the paper and the date you retrieved it. In your paper, use a parenthetical reference with the author's last name and the page number. Keep reading for tips on Chicago and AMA citations and exceptions to the citation rules! Did this summary help you? Yes No

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• Citing Sources

Citing Sources: What are citations and why should I use them?

What is a citation.

Citations are a way of giving credit when certain material in your work came from another source. It also gives your readers the information necessary to find that source again-- it provides an important roadmap to your research process. Whenever you use sources such as books, journals or websites in your research, you must give credit to the original author by citing the source. 

Why do researchers cite?

Scholarship is a conversation  and scholars use citations not only to  give credit  to original creators and thinkers, but also to  add strength and authority  to their own work.  By citing their sources, scholars are  placing their work in a specific context  to show where they “fit” within the larger conversation.  Citations are also a great way to  leave a trail  intended to help others who may want to explore the conversation or use the sources in their own work.

In short, citations

(1) give credit

(2) add strength and authority to your work

(3) place your work in a specific context

(4) leave a trail for other scholars

"Good citations should reveal your sources, not conceal them. They should honeslty reflect the research you conducted." (Lipson 4)

Lipson, Charles. "Why Cite?"  Cite Right: A Quick Guide to Citation Styles--MLA, APA, Chicago, the Sciences, Professions, and More . Chicago: U of Chicago, 2006. Print.

What does a citation look like?

Different subject disciplines call for citation information to be written in very specific order, capitalization, and punctuation. There are therefore many different style formats. Three popular citation formats are MLA Style (for humanities articles) and APA or Chicago (for social sciences articles).

MLA style (print journal article):  

Whisenant, Warren A. "How Women Have Fared as Interscholastic Athletic Administrators Since the Passage of Title IX." Sex Roles Vol. 49.3 (2003): 179-182.

APA style (print journal article):

Whisenant, W. A. (2003) How Women Have Fared as Interscholastic Athletic Administrators Since the Passage of Title IX. Sex Roles , 49 (3), 179-182.

Chicago style (print journal article):

Whisenant, Warren A. "How Women Have Fared as Interscholastic Athletic Administrators Since the Passage of Title IX." Sex Roles 49, no. 3 (2003): 179-182.

No matter which style you use, all citations require the same basic information:

• Author or Creator
• Container (e.g., Journal or magazine, website, edited book)
• Date of creation or publication
• Publisher 

You are most likely to have easy access to all of your citation information when you find it in the first place. Take note of this information up front, and it will be much easier to cite it effectively later.

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Purdue Online Writing Lab Purdue OWL® College of Liberal Arts

In-Text Citations: The Basics

Welcome to the Purdue OWL

This page is brought to you by the OWL at Purdue University. When printing this page, you must include the entire legal notice.

Copyright ©1995-2018 by The Writing Lab & The OWL at Purdue and Purdue University. All rights reserved. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. Use of this site constitutes acceptance of our terms and conditions of fair use.

Note:  This page reflects the latest version of the APA Publication Manual (i.e., APA 7), which released in October 2019. The equivalent resource for the older APA 6 style  can be found here .

Reference citations in text are covered on pages 261-268 of the Publication Manual. What follows are some general guidelines for referring to the works of others in your essay.

Note:  On pages 117-118, the Publication Manual suggests that authors of research papers should use the past tense or present perfect tense for signal phrases that occur in the literature review and procedure descriptions (for example, Jones (1998)  found  or Jones (1998)  has found ...). Contexts other than traditionally-structured research writing may permit the simple present tense (for example, Jones (1998)  finds ).

APA Citation Basics

When using APA format, follow the author-date method of in-text citation. This means that the author's last name and the year of publication for the source should appear in the text, like, for example, (Jones, 1998). One complete reference for each source should appear in the reference list at the end of the paper.

If you are referring to an idea from another work but  NOT  directly quoting the material, or making reference to an entire book, article or other work, you only have to make reference to the author and year of publication and not the page number in your in-text reference.

On the other hand, if you are directly quoting or borrowing from another work, you should include the page number at the end of the parenthetical citation. Use the abbreviation “p.” (for one page) or “pp.” (for multiple pages) before listing the page number(s). Use an en dash for page ranges. For example, you might write (Jones, 1998, p. 199) or (Jones, 1998, pp. 199–201). This information is reiterated below.

Regardless of how they are referenced, all sources that are cited in the text must appear in the reference list at the end of the paper.

In-text citation capitalization, quotes, and italics/underlining

• Always capitalize proper nouns, including author names and initials: D. Jones.
• If you refer to the title of a source within your paper, capitalize all words that are four letters long or greater within the title of a source:  Permanence and Change . Exceptions apply to short words that are verbs, nouns, pronouns, adjectives, and adverbs:  Writing New Media ,  There Is Nothing Left to Lose .

( Note:  in your References list, only the first word of a title will be capitalized:  Writing new media .)

• When capitalizing titles, capitalize both words in a hyphenated compound word:  Natural-Born Cyborgs .
• Capitalize the first word after a dash or colon: "Defining Film Rhetoric: The Case of Hitchcock's  Vertigo ."
• If the title of the work is italicized in your reference list, italicize it and use title case capitalization in the text:  The Closing of the American Mind ;  The Wizard of Oz ;  Friends .
• If the title of the work is not italicized in your reference list, use double quotation marks and title case capitalization (even though the reference list uses sentence case): "Multimedia Narration: Constructing Possible Worlds;" "The One Where Chandler Can't Cry."

Short quotations

If you are directly quoting from a work, you will need to include the author, year of publication, and page number for the reference (preceded by "p." for a single page and “pp.” for a span of multiple pages, with the page numbers separated by an en dash).

You can introduce the quotation with a signal phrase that includes the author's last name followed by the date of publication in parentheses.

If you do not include the author’s name in the text of the sentence, place the author's last name, the year of publication, and the page number in parentheses after the quotation.

Long quotations

Place direct quotations that are 40 words or longer in a free-standing block of typewritten lines and omit quotation marks. Start the quotation on a new line, indented 1/2 inch from the left margin, i.e., in the same place you would begin a new paragraph. Type the entire quotation on the new margin, and indent the first line of any subsequent paragraph within the quotation 1/2 inch from the new margin. Maintain double-spacing throughout, but do not add an extra blank line before or after it. The parenthetical citation should come after the closing punctuation mark.

Because block quotation formatting is difficult for us to replicate in the OWL's content management system, we have simply provided a screenshot of a generic example below.

Formatting example for block quotations in APA 7 style.

Quotations from sources without pages

Direct quotations from sources that do not contain pages should not reference a page number. Instead, you may reference another logical identifying element: a paragraph, a chapter number, a section number, a table number, or something else. Older works (like religious texts) can also incorporate special location identifiers like verse numbers. In short: pick a substitute for page numbers that makes sense for your source.

Summary or paraphrase

If you are paraphrasing an idea from another work, you only have to make reference to the author and year of publication in your in-text reference and may omit the page numbers. APA guidelines, however, do encourage including a page range for a summary or paraphrase when it will help the reader find the information in a longer work. 

Want to create or adapt books like this? Learn more about how Pressbooks supports open publishing practices.

8-How to Cite Sources

4. When to Cite

Citing sources is often described as a straightforward, rule-based practice. But in fact, there are many gray areas around citation, and learning how to apply citation guidelines takes practice and education. If you are confused by it, you are not alone – in fact you might be doing some good thinking. Here are some guidelines to help you navigate citation practices.

Cite when you are directly quoting. This is the easiest rule to understand. If you are stating word-for-word what someone else has already written, you must put quotes around those words and you must give credit to the original author. Not doing so would mean that you are letting your reader believe these words are your own and represent your own effort.

Cite when you are summarizing and paraphrasing. This is a trickier area to understand. First of all, summarizing and paraphrasing are two related practices but they are not the same. Summarizing is when you read a text, consider the main points, and provide a shorter version of what you learned. Paraphrasing is when you restate what the original author said in your own words and in your own tone. Both summarizing and paraphrasing require good writing skills and an accurate understanding of the material you are trying to convey. Summarizing and paraphrasing are difficult to do when you are a beginning academic researcher, but these skills become easier to perform over time with practice.

Cite when you are citing something that is highly debatable. For example, if you want to claim that the Patriot Act has been an important tool for national security, you should be prepared to give examples of how it has helped and how experts have claimed that it has helped. Many U.S. citizens concerned that it violates privacy rights won’t agree with you, and they will be able to find commentary that the Patriot Act has been more harmful to the nation than helpful. You need to be prepared to show such skeptics that you have experts on your side, too.

Tip: Why Cite Sources?

This section covers how and when to cite sources. For a discussion of why to cite sources, see Ethical Use of Sources .

When Don’t You Cite?

Don’t cite when what you are saying is your own insight. As you learned in  The Purpose of Academic Argument , research involves forming opinions and insights around what you learn. You may be citing several sources that have helped you learn, but at some point you must integrate your own opinion, conclusion, or insight into the work. The fact that you are not citing it helps the reader understand that this portion of the work is your unique contribution developed through your own research efforts.

Don’t cite when you are stating common knowledge. What is common knowledge is sometimes difficult to discern. In general, quick facts like historical dates or events are not cited because they are common knowledge.

Examples of information that would not need to be cited include:

• The Declaration of Independence was signed in 1776.
• Barack Obama became the 44th president of the United States in January, 2009.

Some quick facts, such as statistics, are trickier. For example, the number of gun-related deaths per year probably should be cited, because there are a lot of ways this number could be determined (does the number include murder only, or suicides and accidents, as well?) and there might be different numbers provided by different organizations, each with an agenda about gun laws.

A guideline that can help with deciding whether or not to cite facts is to determine whether the same data is repeated in multiple sources. If it is not, it is best to cite.

The other thing that makes this determination difficult might be that what seems new and insightful to you might be common knowledge to an expert in the field. You have to use your best judgment, and probably err on the side of over-citing, as you are learning to do academic research. You can seek the advice of your instructor, a writing tutor, or a librarian. Knowing what is and is not common knowledge is a practiced skill that gets easier with time and with your own increased knowledge.

Tip: Why You Can’t Cite Wikipedia

You’ve likely been told at some point that you can’t cite Wikipedia, or any encyclopedia for that matter, in your scholarly work.

The reason is that such entries are meant to prepare you to do research, not be evidence of your having done it. Wikipedia entries, which are tertiary sources, are already a summary of what is known about the topic. Someone else has already done the labor of synthesizing lots of information into a concise and quick way of learning about the topic.

So while Wikipedia is a great shortcut for getting context, background, and a quick lesson on topics that might not be familiar to you, don’t quote, paraphrase, or summarize from it. Just use it to educate yourself.

Activity: To Cite or Not to Cite?

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Choosing & Using Sources: A Guide to Academic Research Copyright © 2015 by Teaching & Learning, Ohio State University Libraries is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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Using Information Sources Ethically and Legally

• Understanding Plagiarism
• Avoidance Tips

When do I need to cite sources?

Does everything need to be cited, all you need to know about citing sources, get help from libraries and writing centers.

Always give credit where credit is due. If the words that you are including in your research belong to someone else, give credit. 

Here is  a brief list of what needs to be credited or documented :  

• Words or ideas presented in a magazine, book, newspaper, song, TV program, movie, website, computer program, letter, advertisement, or any other medium  
• Information you gain through interviewing or conversing with another person, face to face, over the phone, or in writing  
• When you copy the exact words or a unique phrase  
• When you reprint any diagrams, illustrations, charts, pictures, or other visual materials  
• When you reuse or repost any digital media, including images, audio, video, or other media  

There are certain things that  do not need documentation or credit, including :  

• Writing your own lived experiences, your own observations and insights, your own thoughts, and your own conclusions about a subject  
• When you are writing up your own results obtained through lab or field experiments  
• When you use your own artwork, digital photographs, video, audio, etc.  
• When you are using "common knowledge," things like folklore, common sense observations, myths, urban legends, and historical events (but  not  historical documents)  
• When you are using generally accepted facts (e.g., pollution is bad for the environment) including facts that are accepted within particular discourse communities (e.g., in the field of composition studies, "writing is a process" is a generally accepted fact).  

(From Plagiarism FAQs - Purdue Writing Lab )

The following chart from the UT Arlington Library Acknowledging Sources tutorial will guide you in your decision:

What is common knowledge? This refers to facts well known by many people and verifiable in five or more sources. Examples:

• Bill Gates is the founder of the Microsoft Corporation.
• There are 60 minutes in an hour.
• Columbus is the capital of Ohio.
• The whole is greater than the part.
• Common Knowledge inforgraphic

If you have any doubts or questions, ask your professor or librarian. Err on the side of caution: when in doubt, cite!

The online guide Citing Your Sources provides information on citation, style guides, citation tools, and more.

• Ask a Question (UC Libraries form) Email you reference question and get a response within 24 hours.
• Subject librarians Contact a specialist in your discipline.

Writing Centers

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AWC Tutor Feedback (submit a paper of six double-spaced pages or less and get  feedback from a tutor within 48 hours)

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• UC Clermont Learning Commons Support Services

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Submit your work (submit a paper of six double-spaced pages or less and get  feedback from a tutor within 24-48 hours)

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Warning: when you must cite.

Although you should use sources creatively and flexibly to help you generate ideas and sharpen your argument, there are some hard-and-fast rules about the way sources should be acknowledged in your project. Click on the links for more explanation of the various rules.

ALWAYS CITE, in the following cases:

• When you quote two or more words verbatim, or even one word if it is used in a way that is unique to the source. Explanation
• When you introduce facts that you have found in a source. Explanation
• When you paraphrase or summarize ideas, interpretations, or conclusions that you find in a source. For more explanation, see Fair Paraphrase .
• When you introduce information that is not common knowledge or that may be considered common knowledge in your field, but the reader may not know it. For more information, see Common Knowledge .
• When you borrow the plan or structure of a larger section of a source’s argument (for example, using a theory from a source and analyzing the same three case studies that the source uses). Explanation
• When you build on another’s method found either in a source or from collaborative work in a lab.  Explanation
• When you build on another’s program in writing computer code or on a not-commonly-known algorithm. Explanation
• When you collaborate with others in producing knowledge. Explanation

1. When you quote two or more words verbatim, or even one word if it is used in a way that is unique to the source.

Most writers realize that they must acknowledge a source when quoting a memorable phrase or sentence. They’d be sure to credit Mark Twain when quoting: “The coldest winter I ever spent was a summer in San Francisco.” And you probably also understand that you do not need to cite words that are very common to your topic. When writing about Hamlet, you do not need to put the words “Hamlet” or “Shakespeare” in quotation marks, or cite a source for them, even though you may have read sources that use these words. But when a single word or two are used in a distinctive way, so that the author is creating a new concept or applying it to a new topic, you must give acknowledge the source. When John Baker redefines the significance of the mirror test by saying that chimpanzees’ awareness of their reflection is not full consciousness, but a limited “kinesthetic self-concept,” it’s clear that those two words, as specialized terms of art, should appear in quotation marks in your paper. Even though neither “kinesthetic” nor “self-concept” is unusual on its own, as a phrase they belong to the author. But even a single, non-specialist term—such as “consilience”—may become tied to an author (in this case, E.O. Wilson) through an influential publication, in which case you should put the single word in quotation marks, at least in your first mention of it in your text.

2. When you introduce facts that you have found in a source.

Facts that are generally accessible (the date of the Declaration of Independence, for instance) need not be cited to a particular source, but once you go up one level of detail on the information ladder, you probably need to cite the source (the number of people who signed the Declaration, for instance). And note that commonly known facts found in a particular or unusual context should be cited, so that the reader knows how your argument may have been influenced by the context in which you found it. For more, see Common Knowledge .

3. When you paraphrase or summarize ideas, interpretations, or conclusions that you find in a source. For more explanation, see Fair Paraphrase .

4. when you introduce information that is not common knowledge or that may be considered common knowledge in your field, but the reader may not know it. for more information, see common knowledge ., 5. when you borrow the plan or structure of a larger section of a source’s argument (for example, using a theory from a source and analyzing the same three case studies that the source uses)..

You may not be used to thinking of the plan of a source as proprietary to its author, but if you follow a source’s plan too closely without acknowledging that you saw it there first, you’re presenting as your own an analysis that someone else shaped. For example, if use Mark Hauser’s discussion of primates’ knowledge of other minds from Wild Minds and you discuss the same three experiments that he analyzes, then you must acknowledge this debt. The simplest way to do this is to say “Like Mark Hauser, I find the three experiments carried out by X, Y, and Z groups to be useful in considering the extent of chimpanzee awareness.” An even better way—because it highlights your distinctiveness as a writer—is to distinguish the different use to which you will put the analysis. If, for instance, you’re focusing on primate social skills rather than strictly on their awareness of other minds, you might write: “Mark Hauser examines three experiments carried out by X, Y, and Z for what they can tell us about knowledge of other minds. For my purposes, though, these same experiments shed important light on the social capacities of primates.” These statements can come in a discursive footnote or in the main body, although if the statement distinguishes your argument from the source’s, it has an important role in the body of the argument.

See Gordon Harvey, Writing With Sources , Chapter 3, for an excellent discussion of unfair borrowing of another’s plan.

6. When you build on another’s method found either in a source or from collaborative work in a lab.

Relying on someone’s research method is like #5 above—borrowing a text’s plan or structure. If your approach to a problem is inspired by someone else’s work on a similar or analogous case, credit the original researcher. Building on the work of others is appropriate and desirable, but methods, like specific words and phrases, are a form of intellectual property.

7. When you build on another’s program or on a not-commonly-known algorithm in writing computer code.

Although writing code may seem different from writing papers, the same standards of acknowledgment apply. If you rely on someone else’s program, you must credit that person. Some software algorithms are so well known that they rise to the level of Common Knowledge . Programmers use such pieces of code without acknowledgement. But if the code is not well known, someone reading your program might think you’ve authored parts that are borrowed. For a useful example of unauthorized code borrowing, see this page of the Princeton University website .

8. When you collaborate with others in producing knowledge.

You may sometimes co-author a paper or other text during college; these opportunities are often more frequent in the professional world. When two or more people all contribute substantially to a piece, they normally list all their names as authors. But there are also occasions when someone gives help that does not rise to the level of co-authorship. If you work with a lab partner to set up an experiment, for instance, but run and analyze the results yourself, you should credit the lab partner in a footnote or by reference within your paper. Similarly, if you and a partner present a scene from a play, and you later write a paper using some of the insights you gained during production, you should credit the other actor.

University life is structured so that your ideas will receive constant testing and refinement in discussion with others. You do not need to cite in your papers every conversation you have about the ideas or evidence. But you do need to develop a judgment about which conversations are incidental and which result in ideas that merit reference in your texts. If you take this warning as an opportunity, and make an effort to reveal the trail of your thinking in footnotes and acknowledgements, you’ll soon develop a sense of how to credit collaboration appropriately.

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A handbook for students, search form, what is common knowledge.

You may have heard people say that you do not have to cite your source when the information you include is “common knowledge.” But what is common knowledge?

Broadly speaking, common knowledge refers to information that the average, educated reader would accept as reliable without having to look it up. This includes:

• Information that most people know , such as that water freezes at 32 degrees Fahrenheit or that Barack Obama was the first American of mixed race to be elected president.
• Information shared by a cultural or national group , such as the names of famous heroes or events in the nation’s history that are remembered and celebrated.
• Knowledge shared by members of a certain field , such as the fact that the necessary condition for diffraction of radiation of wavelength from a crystalline solid is given by Bragg’s law.
• However, what may be common knowledge in one culture, nation, academic discipline or peer group may not be common knowledge in another.

How do I determine if the information I am using is common knowledge?

To help you decide whether information can be considered common knowledge, ask yourself:

Who is my audience?

What can I assume they already know?

Will I be asked where I obtained my information?

Some examples:

A description of the symptoms of Asperger’s Syndrome would need to be cited for a composition in a general writing class but probably not need citation for an audience of graduate students in psychology.

A reference to the practice of fair value accounting would be understood by a group of economists, but would need citation to an audience of non-experts.

A statement reporting that 24% of children under the age of 18 live in   households headed by single mothers would need to be cited.  This is information that would not be known to the average reader, who would want to know where the figure was obtained.

The best advice is: When in doubt, cite your source.

Which of the following statements would be considered common knowledge  which would need to be cited.

The Big Bang theory posits that the universe began billions of years ago with an enormous explosion.

The phrase “Big Bang” was coined by Sir Fred Hoyle, an English astronomer.  Hoyle used the term to mock the theory, which he disagreed with.

According to the Big Bang model, the initial explosion was produced when an infinitely hot, dense center referred to as a singularity, began to expand, giving rise to the particles that eventually formed into our universe.

• Statement #1 is common knowledge – the Big Bang theory is widely accepted among scientists and the term is used regularly in everyday speech.
• Statement #2 needs citation; this information is very specific and may even be unknown to some physicists.
• Statement #3 would not need citation to an audience of physics students but would need citation in a paper for a non-expert audience.

What is not Common Knowledge?

Datasets generated by you or others.

Statistics obtained from sources such as the US Census Bureau and the Bureau of Labor Statistics.

References to studies done by others.

Reference to specific dates, numbers, or facts the reader would not know unless s/he had done the research.

Examples of statements that need citation - each refers to work done by others, statistics, or specific information that would not be known by the average reader:

Researchers have found that dispersants utilized to clean up oil spills can lead to lung damage when airborne particles of these dispersants combine with crude oil and are inhaled.

(Source: Wang, H., Shi, YL, Major, D. and Yang, HL (2012, August).  Lung epithelial cell death induced by oil-dispersant mixtures. Toxicology in Vitro, 26, 5, 746-751.  doi: 10.1016/j.tiv.2012.03.011)

A recent study done by scholars at the Brookings Institute found that the number of people living in poverty in America grew by 12.3 million between 2000 and 2010, so that by the end of 2010, 15% of the population was living under the poverty line.

(Source:  Kneebone, E., C. Nadeau and Berube, A.  (2011, November 3).  The re-emergence of concentrated poverty:  metropolitan trends in the 2000s.  Brookings Metropolitan Opportunity Series. Retrieved from http://www.brookings.edu/research/papers/2011/11/03-poverty-kneebone-nadeau-berube .)

The energy of mixing per site for a binary polymer blend with differing degrees of polymerization can be described through the Flory-Huggins equation.

(Source:  Flory, P.J. (1953).  Principles of Polymer Chemistry.  Ithaca, NY: Cornell University Press.)

Note: This equation is specific to the thermodynamics of macromolecular structures and would not be considered common knowledge by many scientists or engineers. For these reasons, they need to be cited.