Stewart, Calculus, Early Transcendentals, Volume 1. Customized version for University of Massachusetts-Amherts. Thomson (Brooks/Cole), 2006. This is a paperback version of the 5th edition. Make sure you have the CORRECT EDITION of the textbook. Homework problems will be taken from the mentioned edition. I was told that the bookstore ran out of copies of the 5-th edition. I suggest if you cannot find the correct edition that you buy the 6-th edition.