Regents review books are study guides specifically designed to help students prepare for the New York State Regents exams. These books typically cover the key concepts and topics that students need to know for each subject area, such as math, science, social studies, and English. They often include practice questions, sample exams, and tips for test-taking strategies. Some popular Regents review book series include Barron's Regents Exams and Answers and Princeton Review's Cracking the Regents Exams. These books can be found in bookstores, online retailers, and in school libraries.