The encyclopedias in these collections are a great way to start the "presearch" process for your research projects. They are useful in familiarizing yourself with an issue or topic and for beginning to learn the terminology of a specific discipline.
The database(s) you search should be dependent on what topic or issue you're researching. Note that these are a few of the databases that are regularly useful for topics in Women, Gender, and Sexuality Studies, but they are not inclusive of all the databases that you might want to consider.