In addition to a book's author and title it is very useful to know the year of publication.
A review is typically written that year or the following year. Books are often reprinted or go through several editions, and they usually include a publication history in the front matter. But these subsequent iterations of a book are most often not reviewed. It is typically in the year that a book initially appears when it gets the most attention.
But maybe your assignment is to locate book reviews without first knowing which book. Either way proceed to Step 2.