Did you know that you can use Subject Headings to search for books? A subject heading is like a tag that pulls together books on a subject, regardless of what specific words or terms the author used. So different authors may use the term "gay" or "homosexual man" or "MSM" to refer to a group of people, but all of those books would be under the subject heading "Gay men". If you only did a keyword search, you might not get all the results.
To search by subject heading, type in SU: before the term. Examples:
For a list of LGBTQ-related subject headings, visit this website: https://secularlibrarian.com/lgbtq-lcsh/.
Caveat: Subject headings can be complicated when talking about LGBTQ topics, because sometimes the nuances of terms can be lost. Changes in subject headings are also slow, so there may be some terms that are no longer considered respectful or accurate still used as subject headings.