WATS 4931/6921 has no required text. WATS 4930/6920 & WATS 6915 share the same required text book:
Dr. Bolstad has put a lot of resources associated with this book online for free.
See here for reading assignments.
six C's you will be graded on are based on principles outlined in this book that a 3 year old can understand!Rabe, T., 2002. There's a Map on my Lap! All About Maps. Random House Books. 48 pp.