For sources with three or more authors, the first author is given followed by et al.

• According to a previously mentioned survey, it also appears that . . . (Norling et al., 2010).
• Norling et al. (2010) further state that . . .

If two citations are the same, add as many author names as necessary to make the citations different:

• This has both Kapoor, Bloom, Montez, et al. (2017) and Kapoor, Bloom, Zucker, et al. (2017) reported on.