For providing in-text references when using the style guide of the American Psychological Association (APA), use the following rules:

• 1 or 2 authors: Use all names every time they’re cited – e.g. ‘Smith and Jones (1998)’

• 3 to 5 authors: Use all names the first time, then the first name followed by et al. – e.g. ‘Jones, Smith, Baxter, Benz, and Ploy (1998)’, and, for subsequent uses, ‘Jones et al. (1998)’

• 6 or more authors: Use first name followed by et al. – e.g. ‘Smith et al. (1998)’