The authors wish to extend sincere thanks for proofreading and useful suggestions to Dr. Michael Engber, professor emeritus at the City College of the City University of New York; Dr. Manfred Kronfeller, professor of mathematics at Vienna University of Technology, Austria; Dr. Bernd Thaller, professor of mathematics at Karl Franzens University–Graz, Austria; and Dr. Peter Schöpf, professor of mathematics at Karl Franzens University–Graz, Austria. We are especially grateful to Dr. Robert A. Chaffer, professor of mathematics at Central Michigan University for contributing chapter 10 on fractals. We also thank Catherine Roberts-Abel for managing the production of this book and Jade Zora Ballard for her meticulous editing.