Citing Sources

Citations provide information to help your audience locate the sources you consulted when writing a paper or preparing a presentation. Some of your instructors will specify which citation format you should use; others will tell you to choose your own citation format as long as you use it consistently. The most common citation formats are MLA (Modern Language Association) style, which is primarily used for papers in the humanities; APA (American Psychological Association) style, which is primarily used for papers in the social sciences; and Chicago style (The Chicago Manual of Style), which is used for both humanities and social science papers.

Some of your courses at Harvard will require you to use other citation formats. Some science courses may require you to use the citation style of the American Medical Association (AMA). AMA style is considered a standard citation format for academic writing in the sciences and is used in many textbooks and medical journals. The AMA Manual of Style is available online. The American Chemical Society publishes its own style guide, which you may be asked to use in chemistry courses. The Harvard Department of Economics provides students with a departmental style guide, which you can find here. If you are not sure which format to use for a specific course, consult your instructor.

Both APA and MLA styles require you to credit your sources in two ways. First, you must include a parenthetical citation in the text of your paper that indicates the source of a particular quotation, paraphrased statement or idea, or fact; second, you must include a list of references at the end of your paper that enables readers to locate the sources you have used. You can read more about MLA style here and APA style here.

Chicago style also requires you to credit your sources both in the text and at the end of your paper. Chicago offers guidance on two types of in-text citations–notes or parenthetical citations. You can read more about Chicago style here.