Citation Guide: Chicago Manual of Style (Author/Date System)

Examples of Variations to In-Text Formatting Rules

1. Citing Sources with No Date

Format: When you cite a source that has no date given, include in parentheses the name of the author and the abbreviation "n.d." ("no date").


This has occurred in previous experiments (Phelps & Gomez, n.d.).

2. Citing Sources with Unnamed, Uncertain or Anonymous Authors

Format: When no author is listed on the tile or copyright page, begin the entry with the title of the work. In the bibliography, alphabetize the entry by the first word other than A, An, or The.

Example One:

Letting Ana Go (New York: Simon Pulse, 2013), 118-20.

Example Two:

Letting Ana Go. New York: Simon Pulse, 2013.

3. Citing Electronic (Web site or Internet) Sources

Format: An electronic source is cited like any other source when the entire source is cited: Author's Last Name and Date of Publication are mentioned. However, in cases where specific parts of the electronic source are cited, documentation of the particular paragraph number or section heading where the cited material may be found is recommended.


Mendelson, Abby. “Roberto Clemente: A Form of Punishment.” Pittsburg Pirates. May 24, 2013.

4. Citing Authors with Same Last Name in References List

Format: Include first name initials of all in-text cited authors when other authors in your References List have the same last name.


K.K. Sullivan (1962) and D. Sullivan (1996) came to similar conclusions about the effects of this treatment method.

5. Citing Sources Not Included in the References List

Format: Unpublished manuscripts, letters and newspaper articles, etc. may be cited within the in-text parenthetical citation or in the actual text itself.

Example One:

Paul Nesbitt (telephone interview, 19 August 2016) expressed his dissatisfaction with the proposed plan.

Example Two:

In a letter dated 12 August 2016, Nesbitt indicated to his daughter that a new plan was being presented to the County Commissioners.

6. Citing Sources with More than One Author

Format, Sources with Two or Three Authors: List the authors in the order in which they appear on the title page. In a note, list the first name for each author first. In the bibliography, list the first author’s last name first and list the first names for each other author first.


Jerin, Robert A., and Laura J. Moriarty. The Victims of Crime. Upper Saddle river, NJ: Pearson Prentice Hall, 2010.

Format, Sources with Four or More Authors: In a note, give only the first author’s name followed by “et al.” (Latin for “and others”). In the bibliography, list all the authors that appear on the title page.

Example One:

Harry Markopolos et al., No One Would Listen: A True Financial Thriller (Hoboken, NJ: Wiley, 2010). 179.

Example Two:

Markopolos, Harry, Frank Casey, Neil Chelo, Gaytri Kachroo, and Michael Ocrant. No One Would Listen: A True Financial Thriller. Hoboken, NJ: Wiley, 2010.

Note: An alternative would be to include a shortened title following the "Author et al.", in every instance of the same "Author et al." occurring.


(Nesbitt et al., Neighborhood associations, 2015)

(Nesbitt et al., Zoning laws, 2015)

7. Citing Sources Authored by a Group or Corporation

Format: Use the group or corporation as the author; it may also be the publisher.


Where the References List entry looks like:

Bas Bleu Theatre Company. 2014. 2014 NEA Grant Application for

The first in-text citation will look like:

The grant proposal (Bas Bleu Theatre Company [BBTC] 2014) was an important effort to support the arts in the community.

And a subsequent in-text citation will look like:

The proposal requested new and increased salaries for theatre staff (BBTC 2014).

8. Citing Two or More Sources in the Same Parenthesis

Format, Two or More Sources by Same Author: When you are citing two or more works by the same author in one parenthetical note, list the name of the author only once, followed by the publication dates of the various works in order of year of publication.


Psychologists have arrived at this conclusion in the past (Tripp, 2004, 2010, 2016).

Format, Two or More Sources Published by Same Author in Same Year: When, in one parenthetical note, you are citing two or more works by the same author published in the same year, be sure to distinguish between the two by assigning them letter suffixes ("a," "b," etc.). These designations will be consistent with those you have given the works in the reference list.


Past research (Johnson 2013a, 2013b) has revealed interesting patterns.

Format, Two or More Sources by Different Authors: When you refer to works by different authors within the same parenthetical note, separate them by using semicolons.


Several studies (Evens 2005; Dorer 2014; Bundy 2014) have contributed to our current understanding of this phenomenon.

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