Use these databases to start finding the materials that are available to you in a multidisciplinary databases. Searching these databases are good places to identify subject headings and to gage the amount of literature availalble on your topic.
This database is the primary source for dissertations and theses. It covers every doctoral dissertation completed in the U.S. at accredited institutions for the last 150 years and includes some master's theses and foreign language dissertations.
Scopus is the largest abstract and citation database of peer-reviewed literature: scientific journals, books and conference proceedings and features tools to track, analyze, and visualize research.