The raison d'être of scholars is to attempt to describe, explain, interpret and analyze issues & events. Scholars use evidence to support their interpretations which are most often published in the form of books and journal articles (secondary sources). So why should you use secondary sources?
Keep in mind
On the results screen use the "Resource Type" options on the left toolbar to limit your results to books. This will eliminate any book reviews and articles that were found. Note down the library name and call number -- you need this information to locate the book.