A citation is a formal reference to a published or unpublished source that you consulted and obtained information from while writing your research paper. The way in which you document your sources 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 method [e.g., law].
Citations document for your readers where you obtained your material, provide a means of critiquing your study based on the sources you used, and create an opportunity to obtain information about prior studies of the research problem under investigation. The act of citing sources is also your best defense against allegations of plagiarism.
Citing the works of others is important because:
NOTE: In any academic writing, you are required to identify which ideas, facts, thoughts, and concepts are yours and which are derived from the research and work of others. Whether you summarize, paraphrase, or use direct quotes, if it's not your original idea, the source must be acknowledged. The only possible 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]. Appreciate, however, that any "commonly known fact" is culturally constructed and shaped by social and aesthetical biases. If you are in doubt about whether or not a fact is common knowledge, protect yourself from an allegation of plagiarism and provide a supporting citation, or, ask your professor for clarification about how a factual statement should be cited.
Ballenger, Bruce P. The Curious Researcher: A Guide to Writing Research Papers. 7th edition. Boston, MA: Pearson, 2012; 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.
Referencing your sources means systematically showing what information or ideas you are quoting or paraphrasing 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.
Procedures used to cite sources vary among different fields of study. 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].
1. Should I avoid referencing other people's work?
No! If placed in the proper context, referencing 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 about the topic, thereby, undermining the validity of your study and your credibility as a researcher. Including references in academic writing not only defends you against allegations of plagiarism, but it is one of the most important ways to demonstrate your knowledge and understanding of previous investigations about the research problem. It is the intellectual packaging around which you present your study to the reader.
2. What should I do if I find that my idea has already been examined by another researcher?
Do not ignore another author's work because doing so will lead your readers to believe that you have either borrowed the idea or information without properly referencing it [this is plagiarism] or that you have failed to conduct a thorough review of the literature. You can acknowledge the other research by writing in the text of your paper something like this: [see also Smith, 2002], then citing the complete source in your list of references. Use the discovery of prior research 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]. Reacting to prior research can include: stating how your study updates previous studies on the topic, offering a new or different perspective, using a different method of data gathering, and/or describing a new set of 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 Smith ...," or "summarized from Smith ...." 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 work of others by stating something similar to the following example: "Though in fact many scholars have applied this theory to understanding economic relations among nations [for example, see Smith, 1989; Jones, 1991; Johnson, 1994; Anderson, 2003], little attention has been given to applying the theory to examining the actions 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, 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 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 that there has been significant scholarship devoted to the topic so the reader knows that you are aware of this.
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 introduction of new variables that necessitate a new investigation. If someone else has recently conducted a thorough investigation of precisely the same research problem as you, 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 it directly, referencing the source. Do not see this as a setback or become discouraged if you discover that your brilliant idea or important insight has already been identified by someone else. Identifying an author who has made the same point as you 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 resource used in writing your paper should be cited, regardless of when the study 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 publications. This is particularly true of new or revised editions of books, unless an older edition has unique information not carried over into newer editions. 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 research problem, it probably should be examined and considered in your list of references because the research may have been foundational or groundbreaking 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.
Ballenger, Bruce P. The Curious Researcher: A Guide to Writing Research Papers. 7th edition. Boston, MA: Pearson, 2012; 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.
The following USC Libraries research guide can help you properly cite sources in your research paper:
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.
This is a useful guide concerning how to properly cite images in your research paper.
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]
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.
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 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].