Citation Styles

How often do I cite?

  • Remember: one citation at the end of a string of sentences or a paragraph cannot “cover” the entire section.
     
  • Cite a source the first time it is used in each paragraph.
     
  • Every sentence thereafter in the paragraph that uses information from this same source must contain either a signal phrase or a citation clearly indicating where the information came from.
     
    • Note: always use a citation (even if you also use a signal phrase) every time you quote material.

In-text Citation Placement

Where in the sentence does my in-text citation go?

  • If you name your source(s) in a given sentence, a parenthetical citation containing only the year always follows immediately after the name(s) of the author(s). Example: In contrast to earlier work by Abbott and Costello (1999), Laurel and Hardy (2008) propose an altogether different model for optimizing hat density …
     
  • If you do not explicitly name your source(s) in a given sentence, a single parenthetical citation goes at the end of the sentence or clause it covers, (Goffman 1974), inside the punctuation, like this (Melville 1851).
    • “If the sentence ends with a quotation, close the quote, then place the citation between the quotation marks and the punctuation, like this” (Woolf 1931, 14).
       
  • Do not insert spaces between a parenthetical citation and the punctuation that follows it.

In the paragraph below, the  parenthetical in-text citations are highlighted in yellow, and the signal phrases are in blue. Note that the second sentence is common knowledge, whereas the final sentence is clearly the opinion of the author.

Red and yellow are the best colors with which to decorate your restaurant because they induce feelings of hunger (Smith and Jones 2009). Consider popular fast-food chains, which often use red and yellow in their advertising and décor. According to Smith and Jones’ study (2009), restaurant customers felt more energized in red and yellow environments, which encouraged them to order more food. The same study indicated that patrons felt relaxed in blue and purple environments, which encouraged them to “spend more time considering the menu options and eat at a slower pace” (29). Although blue décor can give your restaurant a more casual, laid-back feel (Kramer 1999)Smith and Jones believe it encourages patrons to linger at their tables without ordering additional food or beverages. Accordingly, it is difficult to identify a popular chain restaurant that decorates with calmer hues.

For more information, see the TPO's Citing Responsibly in Chicago Author-Date.

Difference between List of References and a Bibliography

A List of References includes all works cited in a text

A Bibliography lists all works cited and consulted


For papers, check with your professors for their preference. Thesis Processing prefers a List of References for the following: 

  • Thesis
  • Capstone project report
  • MBA report
  • Dissertation

Multiple Works by Same Author

When citing multiple sources by the same author from the same year, list them in alphabetical order by title in the List of References  (ignoring initial "a," "an," or "the") and append a lowercase letter to the year.

R: Hawthorne, Pat. 2006a. The Cannibal’s Dilemma: An Unnatural History of Four Siblings. New York: Penguin.

T: (Hawthorne 2006a)

R: Hawthorne, Pat. 2006b. Having People for Dinner: A Guide for the Home Cook. New York: Penguin.

T: (Hawthorne 2006b)


When citing multiple sources by the same author with different years, list them in chronological order.

R: Hawthorne, Pat. 2006. The Cannibal’s Dilemma: An Unnatural History of Four Siblings. New York: Penguin.

R: Hawthorne, Pat. 2008. Regrets. New York: Penguin.

 

Multiple Sources in One Citation

Examples given for books; follow appropriate style for the source type you are citing.

Source Generic Example with Rules Actual Example
Same author, same year, different sources
Source 1

R: Author Last Name, Author First Name. Year published + a. Title of Book 1 in Title Case and Italics. Place of Publication: Publisher.

T: (Author Last Name year + a, page)

R: Hawthorne, Pat. 2006a. Having People for Dinner: A Guide for the Home Cook. New York: Penguin.

T: (Hawthorne 2006a, 99–100)

Source 2

R: Author Last Name, Author First Name. Year published + b. Title of Book 2 in Title Case and Italics. Place of Publication: Publisher.

T: (Author Last Name year + b)

R: Hawthorne, Pat. 2006b.The Cannibal’s Dilemma: An Unnatural History of Four Siblings. New York: Penguin.

T: (Hawthorne 2006b)

Combined T (both sources): (Author Last Name year + a, year + b) T (both sources): (Hawthorne 2006a, 2006b)
Same author, different year, different sources
Source 1

R: Author Last Name, Author First Name. Year published. Title of Book 1 in Title Case and Italics. Place of Publication: Publisher.

T: (Author Last Name year, page)

R: Hawthorne, Pat. 2006. Having People for Dinner: A Guide for the Home Cook. New York: Penguin.

T: (Hawthorne 2006, 99–100)

Source 2

R: Author Last Name, Author First Name. Year published. Title of Book 2 in Title Case and Italics. Place of Publication: Publisher.

T: (Author Last Name year)

R: Hawthorne, Pat. 2008. Regrets. New York: Penguin.

T: (Hawthorne 2008)
Combined T (both sources): (Author Last Name year 1, year 2) T (both sources): (Hawthorne 2006, 2008)
Different authors, different years within one citation
Combined

Separate two or more references with a semicolon. Ensure all authors appear in list of references

T: (Author 1 Last Name year; Author 2 Last Name year)

T: (Fiddleywink and Snort 2005; Munglesnee, Grumpernickel, and Smith 1995; Otatop 2007).

 

Title Case and Sentence Case Difference

Title Case: To Capitalize or Not: A Brief Tutorial

Sentence case: To capitalize or not: A brief tutorial

When Do I Need to Add Page Numbers?

For direct quotes, add page numbers to the in-text citation only.

Example: (Haynes 2009, 70)


For book chapters, include page-number range in List of References/Bibliography.

Example: Cordesman, Anthony H., Adam Mausner, and David Kasten. 2009. Introduction. In Winning in Afghanistan: Creating Effective Afghan Security Forces, edited by John Smith, 1–12. Washington, DC: Center for Strategic and International Studies.

URLs

  • Include an access date if the source material has no date.
     
  • Always add a period at the end of the URL.
     
  • A URL does not belong in an in text-citation. Ever.

Et al.

  • Up to three authors:
    • In the reference list, include all of them
    • In the text, include all of them
       
  • Four to ten authors:
    • In the reference list, include all of them
    • In the text, list only the first author, followed by et al. (“and others”)
       
  • More than ten authors:
    • In the reference list, include only the first seven, followed by et al.
    • In the text, list only the first author, followed by et al.

Secondary Sources

A secondary source is a source that cites some other work that you discuss in your text.

Whenever possible, consult primary sources and your sources’ sources yourself. Upon investigation of the primary source, you may find you disagree with the secondary source author’s analysis or methods. Only use secondary sources when the primary source is unavailable.


How to Incorporate Secondary Sources

The following passage incorporates a properly credited secondary source. The secondary source information is highlighted in yellow; the primary source information is highlighted in blue.

Walker (2008) describes data collected in 1999 by Miguel Roig that correlates students’ inadequate paraphrasing to poor reading comprehension. Citing Roig’s data, Walker explains that “students do in fact possess skills necessary for paraphrasing but … may be impeded from applying those skills when dealing with rigorous text” (387).

Note: Include  only  the  secondary  source  (the  source  you  consulted)  in  your  reference  list. 

No Date Given

To cite an undated document, use n.d. (no date).