Reference list entries for books, journal articles, or any resource with multiple authors can include up to 20 authors' names before it is necessary to abbreviate.
Number of authors to include in text
In-text citations for works with three (3) or more authors can be shortened to the name of the first author and 'et al.' (and page/para. number as usual).
Important
When abbreviating in-text citations with the use of et al., take care to avoid ambiguity. For example:
(Smith, Jones, & Brown, 2018).
(Smith, Jones, Brown, Anderson, Williams, Wilson, & Andrews, 2018).
Both citations above refer to different works published in the same year. Both could be shortened to simply (Smith et al., 2018), thereby creating confusion as to which work is being cited. To avoid ambiguity, the names of as many authors as necessary to distinguish the sources should be used in each citation before abbreviation with et al. For example:
(Smith, Jones, & Brown, 2018).
(Smith, Jones, Brown, Anderson et al., 2018).
Examples
Referencing a book with two authors
The example below shows how to reference a book with two authors and indicates the different elements needed.
Surname, A., & Surname, A. A. (Copyright date). Title: Subtitle in italic sentence case (edition number if applicable.). Publisher.
Dawson, J., & Lucas, R. M. (1993). Lifestyles of New Zealand forest plants (4th ed.). Victoria University Press.
Example
Reference list entry
Dawson, J., & Lucas, R. (1993). Lifestyles of New Zealand forest plants. Victoria University Press.
In-text citations
Page/paragraph numbers are optional for paraphrased information.
Narrative
Dawson and Lucas (1993) argue that ... (p. 67).
Parenthetical
... (Dawson & Lucas, 1993, p. 67).
Referencing a work with three or more authors
In-text citations for works with three (3) or more authors can be shortened to the name of the first author and 'et al.' (and page/para. number as usual).
Reference list entry
Stillings, N. A., Weisler, S. E., Chase, C. H., Feinstein, M. H., Garfield, J. L., & Rissland, E. L. (1995). Cognitive science: An introduction (2nd ed.). The MIT Press.
In-text citations
Page/paragraph numbers are optional for paraphrased information.
Narrative
Stillings et al. (1995) argue that ... (p. 67).
Parenthetical
... (Stillings et al., 1995, p. 67).
Referencing a work with 21+ authors
List the first 19 authors in correct APA style, followed by an ellipsis (three consecutive dots), then the last author's name in APA style.
Reference list entry
Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Leetmaa, A., ... Joseph, D. (1999). The NCEP/NCAR 40-year reanalysis project. Bulletin of the American Meterological Society, 77(3), 437–471. https://doi.org/fg6rf9
In-text citations
Page/paragraph numbers are optional for paraphrased information.
Narrative
Kalnay et al. (1996) outline ... (p. 438).
Parenthetical
... (Kalnay et al., 1996, p. 438).
