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Bibliography Book Two Authors With The Same Last Name

One author

 Give the author's name and the year of publication. If the author's name is stated in the sentence, only the year is needed.

(Clark 1998)

Clark's (1998) study shows that . . .


Two authors

Give both names separated by 'and'. If the surnames are identical, add the initials.

(Flannigan and McBride 2001)

(Smith TL and Smith UV 1990)


Three or more authors

Give only the first author's name followed by et al. (not in italics) and the year.

(Martinez et al. 1990)

If the first author's name and the years of publications are the same for several references, include enough additional co-author names to eliminate ambiguity. Include a comma after the last name.

(Martinez, Fuentes, et al. 1990)


Multiple works by the same author

For works published in the same year, add alphabetic designators to the year in both the in-text reference and the end reference.

(Anderson 1997a, 1997b)

For works published in different years, place years in chronological sequence separated by commas.

       (McBride 2003, 2007)


 Authors with the same surname

 When authors of 2 works published in the same year have the same surname, include their initials in the in-text citation and separate the names by a semicolon and space.

(Dawson J 1986; Dawson M 1986)


Organizations as authors

If an organizational author is referenced only once or twice in a document, the full organizational name is acceptable. A shortened form can be used in the in-text reference if the organization has a familiar abbreviation.

(Institute of Medicine 1975)

(NSF 2005)

End reference: National Alliance of State and Territorial AIDS Directors (US). 2006.  How to format in text??   (National Alliance . . .

If an organizational author is referenced several times in a document, a shortened form of the organizational name can be used. Use the initial letter of each part of the name or a recognizable abbreviation. Include the abbreviation as the initial element of the end reference within square brackets.

 (IOM 1975)

End reference: [IOM] Institute of Medicine (US). 1975.  


Works without authors

Begin the in-text reference with the first word or first few words of the title, followed by an ellipsis. Use only enough words to distinguish this title from other end references.

(Handbook . . . c2000)

End reference: Handbook of geriatric drug therapy. c2000. Springhouse (PA): Springhouse.


Works with multiple dates

This can occur with journals whose volumes span calendar years, books with several volumes, and electronic documents.

Give the first and last years of publication, separated by a hyphen.

(Johnson L and Johnson BR 1999-2002)

For electronic publications include only one date in the in-text reference in the following order of preference:

  • date of publication
  • date of copyright
  • date of modification, update or revision
  • date of citation 

(Harris et al. [cited 2008])

End reference:

Harris CL, Sheets A, Bigot D. [cited 6 Jun 2008]. Imaging of the Montastrea faveolata [Internet]. Miami (FL): Saveseas. Available from http://www.saveseas.com/.


Works without dates

Place the words 'date unknown' within square brackets in the in-text reference. Include [date unknown] in the end reference also. Rarely, will no date be associated with a publication.

(Brigmeyer [date unknown])

In-Text Citations: Author/Authors


APA (American Psychological Association) style is most commonly used to cite sources within the social sciences. This resource, revised according to the 6th edition, second printing of the APA manual, offers examples for the general format of APA research papers, in-text citations, endnotes/footnotes, and the reference page. For more information, please consult the Publication Manual of the American Psychological Association, (6th ed., 2nd printing).

Contributors: Joshua M. Paiz, Elizabeth Angeli, Jodi Wagner, Elena Lawrick, Kristen Moore, Michael Anderson, Lars Soderlund, Allen Brizee, Russell Keck
Last Edited: 2018-02-21 02:51:57

APA style has a series of important rules on using author names as part of the author-date system. There are additional rules for citing indirect sources, electronic sources, and sources without page numbers.

Citing an Author or Authors

A Work by Two Authors: Name both authors in the signal phrase or in parentheses each time you cite the work. Use the word "and" between the authors' names within the text and use the ampersand in parentheses.

Research by Wegener and Petty (1994) supports...

(Wegener & Petty, 1994)

A Work by Three to Five Authors: List all the authors in the signal phrase or in parentheses the first time you cite the source. Use the word "and" between the authors' names within the text and use the ampersand in parentheses.

(Kernis, Cornell, Sun, Berry, & Harlow, 1993)

In subsequent citations, only use the first author's last name followed by "et al." in the signal phrase or in parentheses.

(Kernis et al., 1993)

In et al., et should not be followed by a period.

Six or More Authors: Use the first author's name followed by et al. in the signal phrase or in parentheses.

Harris et al. (2001) argued...

(Harris et al., 2001)

Unknown Author: If the work does not have an author, cite the source by its title in the signal phrase or use the first word or two in the parentheses. Titles of books and reports are italicized; titles of articles, chapters, and web pages are in quotation marks.

A similar study was done of students learning to format research papers ("Using APA," 2001).

Note: In the rare case the "Anonymous" is used for the author, treat it as the author's name (Anonymous, 2001). In the reference list, use the name Anonymous as the author.

Organization as an Author: If the author is an organization or a government agency, mention the organization in the signal phrase or in the parenthetical citation the first time you cite the source.

According to the American Psychological Association (2000),...

If the organization has a well-known abbreviation, include the abbreviation in brackets the first time the source is cited and then use only the abbreviation in later citations.

First citation: (Mothers Against Drunk Driving [MADD], 2000)

Second citation: (MADD, 2000)

Two or More Works in the Same Parentheses: When your parenthetical citation includes two or more works, order them the same way they appear in the reference list (viz., alphabetically), separated by a semi-colon.

(Berndt, 2002; Harlow, 1983)

Authors With the Same Last Name: To prevent confusion, use first initials with the last names.

(E. Johnson, 2001; L. Johnson, 1998)

Two or More Works by the Same Author in the Same Year: If you have two sources by the same author in the same year, use lower-case letters (a, b, c) with the year to order the entries in the reference list. Use the lower-case letters with the year in the in-text citation.

Research by Berndt (1981a) illustrated that...

Introductions, Prefaces, Forewords, and Afterwords: When citing an Introduction, Preface, Foreword, or Afterword in-text, cite the appropriate author and year as usual.

Personal Communication: For interviews, letters, e-mails, and other person-to-person communication, cite the communicator's name, the fact that it was personal communication, and the date of the communication. Do not include personal communication in the reference list.

(E. Robbins, personal communication, January 4, 2001).

A. P. Smith also claimed that many of her students had difficulties with APA style (personal communication, November 3, 2002).

Citing Indirect Sources

If you use a source that was cited in another source, name the original source in your signal phrase. List the secondary source in your reference list and include the secondary source in the parentheses.

Johnson argued that...(as cited in Smith, 2003, p. 102).

Note: When citing material in parentheses, set off the citation with a comma, as above. Also, try to locate the original material and cite the original source.

Electronic Sources

If possible, cite an electronic document the same as any other document by using the author-date style.

Kenneth (2000) explained...

Unknown Author and Unknown Date: If no author or date is given, use the title in your signal phrase or the first word or two of the title in the parentheses and use the abbreviation "n.d." (for "no date").

Another study of students and research decisions discovered that students succeeded with tutoring ("Tutoring and APA," n.d.).

Sources Without Page Numbers

When an electronic source lacks page numbers, you should try to include information that will help readers find the passage being cited. When an electronic document has numbered paragraphs, use the abbreviation "para." followed by the paragraph number (Hall, 2001, para. 5). If the paragraphs are not numbered and the document includes headings, provide the appropriate heading and specify the paragraph under that heading. Note that in some electronic sources, like webpages, people can use the "find" function in their browser to locate any passages you cite.

According to Smith (1997), ... (Mind over Matter section, para. 6).

Note: Never use the page numbers of webpages you print out; different computers print webpages with different pagination.

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