Where can I find an APA Style guideline that is not mentioned on this site or in the libguide?

The complete official APA Style can be found in this book:

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th Edition).

Various blogs also provide information and explanations.
If in doubt, try to be as complete as possible: remember that the intention of a reference list is to allow someone else to find the listed source. If you are unsure, get in touch with your education institution's Auteursrechten Informatiepunt (AIP, 'Copyright Information Desk').