The Library Search tool is often the best way to find books reviews, especially if you are looking for reviews of a specific book.
1) Search for either the title of a particular book or keywords that you hope will appear in the reviewed book's title.
2) In the left-hand column, under Source Type, select Reviews. Note: if you search by topic keywords, you may also end up with other types of reviews (e.g., movie or play reviews).
America: History and Live/Historical Abstracts and JSTOR both allow you to limit to reviews. In both databases, you need to do this on the advanced search screen BEFORE you search. You can't limit to reviews in either after you search.
On the advanced search screen, scroll down to see the options below the search boxes. Find Publication Type. Review is the last option on the list.
In JSTOR, scroll down until you see the Narrow Results option and select Reviews.