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Sustainability: Health & Environment: Citation

There are numerous formats that can be used to cite sources. Three of the most commonly used formats at Duquesne are:

  • APA - Created by the American Psychological Association, it is mainly used in Psychology and some of the other Social Sciences, as well as Nursing. The current version is the 6th edition.
  • Chicago Manual of Style - Used in many disciplines. The current version is the 17th edition.
  • MLA - Created by the Modern Language Association, it is mainly used in English and may be used in some of the other Humanities. The current version is the 8th edition.

When we speak of citing, two things are meant. The first is citing within the text of a paper, either by using parenthetical references, or footnotes. The second is providing complete bibliographic information for your sources in a bibliography (also known as a Works Cited page or Reference List).

The Duquesne University Writing Center has created very helpful guides to assist you with citing in-text and in bibliographies in MLA, APA, Chicago Manual of Style and MLA. PDFs of these documents are available below.

 APA (6th edition)In-text and Reference List

Chicago, notes and bibliography (17th edition)In-text and Bibliography

Chicago, author-date (17th edition)In-text and Bibliography

MLA (8th): In-text and Works Cited and Formatting


In writing papers, you will often want to use exact quotes, especially when you cannot improve upon an author's original way of stating an idea. In those instances, of course, you should use the exact quotation, correctly citing it as the work of someone else.

But a paper cannot be written by simply stringing together exact quotations from a number of authors. More often than not, in writing you will do more stating the ideas of others in your own words, that is you will paraphase or summarize those ideas of other people.

Paraphrases and summaries of other people's ideas must also be cited, or you will be charged with plarigaism. Plagiarism is not just the using of other people's exact words without giving them credit, but also using their uniques ideas without citing them as the source. Because correct paraphrasing and summarizing can often be confusing to students, the Duquesne University Writing Center has created a handout on these topics. To see a PDF of it, click on the link below.

Paraphrasing, Summarizing, and Quoting


Surprisingly, not everything has to be cited. For example, a statement like "George Washington is known as the 'Father of His Country'" would not need to be cited because this is a general idea in the culture that most people are aware of. These sorts of information are called "common knowledge."

Another way to express this is, if three to five reference works all say the same thing about a topic, then that idea is common knowledge. It is not the intellectual property of any one individual, and, therefore, does not need to be cited. If you ever have questions on whether a statement is common knowledge, Ask a Librarian, talk to your professor, or contact the Duquesne University Writing Center.

For students who are required to cite in Chicago Style, the Gumberg Library offers the entire style guide for online use as a database. To use it off-campus, you will need to enter your Multipass username and password when you click on the link below.