As we mentioned above, your essay will be a mix of your own ideas, information from your research sources, and your responses to or analysis of the information from your sources. You have to cite the information from your research sources so that your reader doesn’t think you’re taking the work and presenting it as your own. But figuring out exactly when a citation is needed can still be difficult. It gets easier with practice. The Decision Tree below shows you the key questions to ask yourself about how you are using research sources so that you can cite appropriately.

Deciding When a Citation is Needed

Review this decision chart that is designed to help you decide when you have to include a citation in your writing. We recommend saving this chart, if possible, so that you can check it when you are writing your outline with citations and when you are drafting your essay. A second copy of the decision chart is included in the Appendix in the section titled “Citing Sources Decision Chart”, so you can easily tear it out and keep it with your papers.

The text version of The Steps to Avoiding Plagiarism is in the Appendix.

As professor of writing Rebecca Moore Howard explains to students to help protect them from being accused of plagiarism, “When in doubt, cite; over-citation is an error, but under-citation is plagiarism” (800).

What about “Common Knowledge?” If you have been taught about citing sources and avoiding plagiarism in the past, you may have heard the term “common knowledge” and you might have been told that you shouldn’t cite something if it’s common knowledge.

Common knowledge is usually defined as the set of knowledge (not opinions or beliefs) that most educated people share. But in reality we all belong to different knowledge communities and there may be common knowledge that is shared by most people within your community that even smart, wise, or educated people outside of your community do not know. For example, people who belong to the same religion will have common knowledge about the holy books of their religion but may not know about the holy books of other religions or about the foundational books in biology or physics. And a community of physicists share common knowledge with each other about the laws of thermodynamics and famous physics experiments but they may not know about holy books that religious people know about and they also may not know how bills become laws the way that political scientists would know it. We could make an infinitely long list of all of the things that some people consider common knowledge and that other people do not know.

So calling something “common knowledge” usually means you’re forgetting how many people are outside of the community that shares that knowledge. Citing a source that taught you something new or gave you a new idea, even if you think that the information you got from it could be considered common knowledge by other people, is also a way to be extra sure no one will think that you plagiarized the information you are providing. On the other hand, if you already know the fact that you find in one of your research sources (for example that Yosemite National Park is in California and is really popular) then you do not need to put an in-text citation when you write that fact into your essay. You can treat that knowledge as your own or think of it as common knowledge, neither of which needs to be cited in order to avoid plagiarism.

Deciding when to cite the source of a fact and when to just state the fact without a citation is a balance that you will have to find after you write several essays and get feedback from several professors. And as you become more of an expert in your field, what you have to cite compared with what you can just state about your topic will continue to evolve because your own knowledge will grow. As a student, the option that has the least risk is always to cite the source of your information.

In-Text Citations and Citations at the End

Every essay has to have both in-text citations and full citations. Just having one or the other is not helpful. The in-text citations that you use to show the boundaries of your paraphrases in your essay do not give your reader all of the information that they need if they want to find the original source that you are citing. That’s why you have to put the full citation for each source at the end of your essay.

Every college essay should include a list of the sources you used. MLA calls this list the Works Cited and APA calls it References, and they mean the same thing. It is an alphabetized list of all of the sources that you cited in your essay. But if you only have a list of the sources you used at the end of your essay, your reader has no way to know where exactly you used each source. So that’s why the in-text citations have to be included throughout your essay.

The following example of the connection between in-text citations and full citations is from the Private Academic Library Network of Indiana Consortium’s Information Literacy Module and it is licensed under a CC-BY License.

Citation is a two part process:

In-text: the information you cite in your paper

Works cited: the complete information about your sources at the end of your paper

Part 1: In-Text Citation

This is what an in-text citation looks like in an essay:

The text version of In-Text Citation Highlights is in the Appendix.

Part 2: Works Cited

Each time you refer to an author’s work in the text of your paper (in-text citation), a corresponding full citation is made at the end of your paper, in the bibliography (called Works Cited in MLA and References in APA).

Works Cited list:

Together, your in-text citations how your reader where you used ideas from others in your essay and your Works Cited List gives your reader all of the information they need to find each source you used.