1. Use the Advanced Search option.
2. Type your search as either a Keyword or Subject.
3. Scroll down to the Format box and choose e-book from the drop-down menu.
An Overview is a book which addresses a time period such as The Sixties Unplugged. Use the index to find your topic; it may be a chapter or just a few pages. An overview is meant to place your topic within the context of the time and larger world.
A Monograph is a book which addresses your specific topic. If you are researching a person, a monograph could be a biography of the person. If you are researching an event, a monograph might be Living the Revolution: the Yippies in Chicago.