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Biology

How to Cite APA

How to Cite: APA


APA style is generally used by the Biology field. It features parenthetical citations and an alphabetized list of references at the end called the Reference List. Entries for the list of works cited must be alphabetical and double-spaced, with the indent of the subsequent line one-half inch from the left margin. 

Please consult your professor for the citation style they prefer. Always follow any specific guidelines given by your professor, even if they differ from what is explained here.

APA Citations

Citing one work by one author: Place the author's last name (no suffixes such as Jr.) in parentheses followed by a comma and the year published. If the author's name is used in the sentence, you should put just the year published in the parentheses immediately following the author's name. 

Example:

Early onset results in a more persistent and sever course (Kessler, 2003).

Kessler (2003) found that among epidemiological samples...

If the author's name is included in the narrative (see second example above) later within the same paragraph, you do not include the year published in the parentheses again. However, if subsequent references to the author in that same paragraph are included in parentheses, you must include the year published every time. If the same author is referenced later in a different paragraph, the reference must include the author's name and the year published as if you are referencing it for the first time.

Citing one work by multiple authors: If a work has 2 authors, cite both authors' names every time following the rules for a work by one author.

Example:

...as Kurtines and Szapocznik (2003) demonstrated...

...as has been shown (Jöreskog & Sörbon, 2007)...

If a work has 3 to 5 authors, cite all authors the first time. In subsequent citations, cite the last name of the first author followed by et al. and the year published (unless the reference with the year has already been made within that paragraph).

Example:

Kisangau, Lyaruu, Hosea, and Joseph (2007) found...[Use as first citation in text.]

Kisangau et al. (2007) found...[Use as subsequent first citation per paragraph thereafter.]

Kisangau et al. found...[Omit year from subsequent citations after first nonparenthetical citation within a paragraph.]

If a work has 6+ authors, cite the last name of the first author followed by et al. and the year published for the first and all subsequent citations.

Example:

Kosslyn, et al. (1996) found...

Citing a work with no identified author or an anonymous author: If a work has no named author, use the first few words of the title in place of the author's name.

Example: 

...on free care ("Study Finds," 2007)...

...the book College Bound Seniors (2008)...

When the author is listed as "Anonymous" you should use the word Anonymous in place of the author's name.

Example:

...on free care (Anonymous, 1998)...

Citing 2 or more works within the same parentheses: For works by the same author, place the author's last name in the parentheses followed by the years published separated by commas.

Example:

Training materials are available (Department of Veterans Affairs, 2001, 2003)...

For works by different authors, list the citations in alphabetical order by the first author's last name. Separate the citations with a semicolon.

Example:

Several studies (Miller, 1999; Shafranske & Mahoney, 1998)...

Periodicals include anything published on a regular basis. Examples are journals, newspapers, and magazines. Articles found in a library database are cited in this format rather than like something found through a search engine like Google. For information on how to cite something found in a search engine, see the "Reference List: The Internet" tab.

General reference form:

Author, A. A., Author, B. B., & Author, C. C. (year). Title of article. Title of Periodical, x(x)pp-pp. doi:xx.xxxxxxxxxx

DOIs should be listed for all electronic works. If no DOI is assigned, use the home page URL.

Author, A. A., Author, B. B., & Author, C. C. (year). Title of article. Title of Periodical, x(x)pp-pp. Retrieved from http://www.example.com

Take note:

No period is placed at the end of the DOI or URL. If you are citing a print work, you end the citation at the page numbers with a period.

Include the issue number in parentheses after the volume number if the journal is paginated by issue rather than volume.

Only the first word of the title and subtitle is capitalized. All other words in the title are lower-case unless they are abbreviations or proper nouns.

If a citation is on 2 or more lines, the 2nd and all subsequent lines should have a hanging indent.

Examples:

Journal article, electronic version cited

Herbst-Damm, K. L., & Kulik, J. A. (2005). Volunteer support, marital status, and the survival times of terminally ill patients. Health Psychology, 24, 225-229. doi:10.1037/0278-6133.24.2.225

Sillick, T. J., & Schutte, N. S. (2006). Emotional intelligence and self-esteem mediate between perceived early parental love and adult happiness. E-Journal of Applied Psychology, 2(2), 38-48. Retrieved from http://ojs.lib.swin.edu.au/index.php/ejap

Journal article, print version cited

Light, M. A., & Light, I. H. (2008). The geographic expansion of Mexican immigration in the United States and its implications for local law enforcement. Law Enforcement Executive Forum Journal, 8(1), 73-82.

Magazine article

Chamberlin, J., Novotney, A., Packard, E., & Price, M. (2008, May). Enhancing worker well-being: Occupational health psychologists convence to share their research on work, stress, and health. Monitor on Psychology, 39(5), 26-29.

Newspaper article

Schwartz, J. (1993, September 30). Obesity affects economic, social status. The Washington Post, pp. A1, A4.

Brody, J. E. (2007, December 11). Mental reserves keep brain agile. The New York Times. Retrieved from http://www.nytimes.com

Format for entire book: (Choose the format that best fits your book.)

Author, A. A. (year). Title of work. Location: Publisher.

Author, A. A. (year). Title of work. Retrieved from http://www.example.com

Author, A. A. (year). Title of work. doi:xxxxx

Editor, A. A. (Ed.). (year). Title of work. Location: Publisher.

Format for chapter in book or entry in reference book: (Choose the format that best fits your book.)

Author, A. A., & Author, B. B. (year). Title of chapter or entry. In A. Editor, B. Editor & C. Editor (Eds.), Title of book (pp. xx-xx). Location: Publisher.

Author, A. A., & Author, B. B. (year). Title of chapter or entry. In A. Editor, B. Editor & C. Editor (Eds.), Title of book​ (pp. xx-xx). Retrieved from http://www.example.com

Author, A. A., & Author, B. B. (year). Title of chapter or entry. In A. Editor, B. Editor & C. Editor (Eds.), Title of book​ (pp. xx-xx). doi:xxxxxxxx

Format for entry in reference work with no byline:

Title of entry. (year). In A. Editor (Ed.) Title of reference work (xx ed., Vol. xx, pp. xx-xx). Location: Publisher.

Take note:

Only the first word of the title and subtitle is capitalized. All other words in the title are lower-case unless they are abbreviations or proper nouns.

If a citation is on 2 or more lines, the 2nd and all subsequent lines should have a hanging indent.

Examples:

Entire book, print version cited

Shotton, M. A. (1989). Computer addiction? A study of computer dependency. London, England: Taylor & Francis.

Entire book, electronic version cited

Shotton, M. A. (1989). Computer addiction? A study of computer dependency [DX Reader version]. Retrieved from http://www.ebookstore.tandf.co.uk/html/index.asp

Book chapter, print version cited

Haybron, D. M. (2008). Philosophy and the science of subjective well-being. In M. Eid & R. J. Larsen (eds.), The science of subjective well-being (pp. 17-43). New York, NY: Guilford Press.

Articles found in a library database are cited as periodicals rather than like something found through a search engine like Google. For information on how to cite something you found in a library database, see the "Reference List: Periodicals" tab.

General reference form:

Author, A. A. (Year, Month Day). title of post [Description of form]. Retrieved from http://www.example.com

Take note: 

Only the first word of the title and subtitle is capitalized. All other words in the title are lower-case unless they are abbreviations or proper nouns.

If a citation is on 2 or more lines, the 2nd and all subsequent lines should have a hanging indent.

If only the author's screen name is available rather than their full name, use their screen name.

Example:

Web page

Volpe, J.S. (1996). Effects of domestic violence on children and adolescents: An overview. Retrieved from http://www.aaets.org/article8.htm

Message posted to a newsgroup, online forum, or discussion group

Rampersand, T. (2005, June 8). Re: Traditional knowledge and traditional cultural expressions [Online forum comment]. Retrieved from http://www.wipo.int/roller.comments/ipisforum/weblog/theme_eight_how_can_cultural#comments

Message posted to an electronic mailing list

Smith, S. (2006, January 5). Re: Disputed estimates of IQ [Electronic mailing list message]. Retrieved from http://tech.groups.yahoo.com/group/forensicnetwork/message/670

Blog post

PZ Myers. (2007, January 22). The unfortunate prerequisites and consequences of partitioning your mind [Web log post]. Retrieved from http://scienceblogs.com/pharyngula/2007/01/the_unfortunate_prerequisites.php

YouTube

Norton, R. (2006, November 4). How to train a cat to operate a light switch [Video file]. Retrieved from http://www.youtube.com/watch?v=vja83klqxzs

General reference form:

Author. (Year, Month Day) Title by individual authors if applicable. (Series) Place Published: Publisher. (Report Number)

Author. (Year, Month Day) Title by individual authors if applicable. (Series) Retrieved from name of website: URL

Take note:

The author of a government document is almost always an institution. When citing a federal agency, start with "United States" or "U.S." as the author followed by the institution. Sometimes there is both an institutional author and one or more individual authors. If this is the case, name the individual authors after the title of the information.

Cite the report number so that the reader can differentiate between it and reports with a similar title.

If the publisher of the document is also the author, listing the shortened name of the publisher is fine.

Be sure to include the URL if the document is retrieved from the web.

Examples:

Online government document:

United States. Federal Reserve Board. (1998, July 22). Conduct of monetary policy; Report of the Federal Reserve Board pursuant to the Full Employment and Balanced Growth Act of 1978; July 21, 1998 report. Retrieved from the Federal Reserve Web site: http://www.federalreserve.gov/boarddocs/hh/1998/july/fullreport.htm