Among the useful print Reference books you can find (using the given call numbers) in the ESC are:
Background Information gives you an introduction to a topic, issue, or person. It's what you're looking for when you look up "Ancient Greece" in an encyclopedia. Knowing a little bit about something you are researching helps you focus in on what's really interesting to you!
So...get a few facts, details, names and terms about your topic...then decide in what direction your curiosity wil take you.