Q. How should I reference an author with "Jr." or "III" in his name?

APA Style (7th ed.)

Place the Jr. or III after the author's first initials in the reference, and place a comma to separate the initials from the suffix (American Psychological Association, 2020, p. 286)

Example

Lastname, A., Jr. (year). Title of resource. Retrieved from URL

Don't include the Jr. or III in the in-text citation: (Lastname, year, p. X).

Reference

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000