General and subject encyclopedias give an overview of a broad range of topics. Featured are samples of subject encyclopedias at the GC Library. Such resources can help you identify more keywords and phrases for your research strategy.
Encyclopedia entries can help you define the scope of research on a given topic and give you ideas for a thesis statement or research question. You may not actually quote information from a reference material, but it is an excellent "jumping off" point when starting a new research endeavor.
Don't forget to mine the "References" or "Further Reading" section of encyclopedia entries to discover quality books, articles, and web resources related to your topic.