A first step to searching for materials on your topic is to talk to experts who can suggest beginning sources to you: your professors and anyone else that they recommend.
There are three useful principals to remember and apply when searching any kind of electronic search tool (a library catalog, a digital library, a database, the internet, etc.)
1. A keyword search in any resource will point you to great initial resources, but you will not find all of the resources you need this way.
2. It is really important that you follow up on your initial searching by:
a) looking at the complete records to identify subject headings or descriptors that you can use to search further
b) carrying out seed research: go to the initial sources and check the footnotes, endnotes, and bibliographies to find further resources. It is also helpful to walk around the shelves in the library where you find initial print sources, as other related sources will be shelved in this area.
3. Use reference sources to start your research as well. There are great electronic and print reference tools (dictionaries, encyclopedias, atlases, and more) that can help you clarify and narrow down your topic and identify great starting resources.
A very helpful place to identify and learn more about different tools to use in keyword searching (including boolean operators, truncation, and subject headings) can be found on the Search Strategies tab of the MCWP 50 & MCWP 125 Research Guide.