The first citation lists all of the authors' names, while the subsequent citations give only the first author’s name followed by "et al."
Remember that when the authors' names occur inside of the parentheses, they are connected with the symbol "&”; but when they occur outside of the parentheses, they are connected with the English word “and".
First Citation:
Templates:
... (Author, Author, & Author, Year).
Author, Author, and Author (Year) ...
Examples:
...(Peters, Clark, & Ball, 2010).
Peters, Clark, and Ball (2010) say...
Subsequent Citations:
Templates
... (Author et al., Year).
Author, et al. (Year) verb ...
Examples
...(Peters et al., 2010).
Peters et al. (2010) say...