Before you start searching for sources, it helps to get some familiarity with your research topic. Background information helps you in several ways:
Narrow and focus your research question
Provide keywords and phrases related to the topic
Background information can sometimes be gathered via googling the topic. However, subject encyclopedias are a great way to get some background information and they're typically written by experts in the field. Note: always check with your professor to see if this source type is permitted for the assignment.
Credo Reference is a ready-reference solution for learners and librarians. Its full-text¸ aggregated content covers every major subject from the world's best publishers of reference materials. The content is enriched with images¸ sound files¸ maps and customizable data tables.
Gale Ebooks (formerly Gale Virtual Reference Library) is a database of encyclopedias and specialized reference sources for multidisciplinary research. These reference materials once were accessible only in the library¸ but now you can access them online from the library or remotely 24/7.
The Core Collection is a huge and comprehensive resource that contains over 100 dictionaries and reference titles covering the complete subject spectrum: from General Reference and Language to Science and Medicine¸ and from Humanities and Social Sciences to Business and Professional.