If your source has three or more authors, your in-text citation should include the first author’s last name followed by et al.
Example:
According to most experts, “the best way to increase a child’s literacy” is to read to them every night (Wolf et al. 220–240).
The first time the authors are mentioned in the text, one option is to list all of the authors’ full names. Alternatively, it is acceptable to mention the first author’s full name with “and colleagues” or “and others” after the name.
Example:
James Wolf and colleagues note that children whose parents read to them every night receive higher scores on literacy tests (220–240).