Q. How do I know if a book is peer reviewed?
To ascertain if a book has been "peer-reviewed"--that is, if it's a reliable academic source--search for book reviews in HoyaSearch, which searches a variety of databases, or in a dedicated article database such as Academic Search Premier or Proquest. You can tailor your search to just look at book reviews, or try a global search using the title of the book.
You can also look at the credentials of the author. Are they a specialist in their field, or a journalist writing an overview? Have they published before on the subject? Finally, look at the publisher--is it an academic press or a trade paperback?
All of this can help you determine the credibility of a source.