Read overviews to quickly grasp the basics of your topic, and to find clues to follow up on (such as citations to other sources). Don't cite overviews.
Read critically! Don't assume that overviews are unbiased.
Overviews are often found in reference books such as encyclopedias. Find these books in the Reference section on the first floor of Simpson Library:
Simpson Library has these books as e-books only:
Some encyclopedias are websites: