Publication Manual (OFFICIAL) 7th Edition of the American Psychological Association by https://apastyle.apa.org/style-grammar-guidelines
"The style and grammar guidelines pages present information about APA Style as described in the Publication Manual of the American Psychological Association, Seventh Edition and the Concise Guide to APA Style, Seventh Edition. Any updates to APA Style are noted on the applicable topic pages. If you are still using the sixth edition, helpful resources are available in the sixth edition archive."