The first place to look when beginning research on a topic is in reference material: specialized dictionaries, encyclopedias or handbooks. These allow you to check names, dates and places, find additional information, look up unknown terms, and check for the proper spelling of words. They are particularly helpful for finding basic background information on a topic, and are often the only place many students may need to look to find answers to their questions. They may include bibliographies (lists of additional materials on a topic, usually considered by the author to be the best materials on that topic or at least the material that author used) that you can use to find other materials.
Soble, Alan. Sex From Plato to Paglia: A Philosophical Encyclopedia. Westport, CT: Greenwood, 2006. Print.
Stanton, Domna C. Discourses of Sexuality: from Aristotle to AIDS. Ann Arbor: University of Michigan Press, 1992.
Gilman, Sander L. Sexuality : an Illustrated History Representing the Sexual in Medicine and Culture From the Middle Ages to the Age of AIDS. New York : Wiley, c1989.
Carstarphen, Meta G and Zavoina, Susan C. Sexual Rhetoric : Media Perspectives on Sexuality, Gender, and Identity. Westport, Conn. : Greenwood Press, 1999.