Below is a search string(s) for your population that you can use to begin a search of CINAHL. Copy and paste the string into the first search box and then use the second search box to explore keywords and subject headings that reflect the cultural aspects/topics of interest.
Caring for Lesbian and Gay People: A Clinical Guide by 
The Health of Lesbian, Gay, Bisexual, and Transgender People: Building a Foundation for Better Understanding by