Reference resources are a great place to begin your research. They can help you define terms as well as to find basic information about a topic, a chronicle of its history, theories, key people and sometimes a bibliography of additional sources.
There are many different types of reference sources, which include dictionaries, encyclopedias, thesauri, bibliographies, handbooks, style manuals to name a few.
Encyclopedia of Gender and Society
REF HQ1115 .E54 2009 (Stauffer Library)
Encyclopedia of Lesbian, Gay, Bisexual, and Transgender History in America
Encyclopedia of Women and Gender : Sex Similarities and Differences and the Impact of Society on Gender
REF HQ1115 .E43 2001 (Stauffer Library)
Global Encyclopedia of Lesbian, Gay, Bisexual, Transgender, and Queer (LGBTQ) History
The Wiley Blackwell Encyclopedia of Gender and Sexuality Studies
Bibliographies like Oxford Bibliographies offer authoritative research guides helping you to narrow the vast number of citations to the best scholarship on a given topic.
There are guides on Gender, Gender and Sexuality, Sexuality to name a few.