I am indebted to Eric Frankl for proofreading the entire manuscript. Eric caught and corrected several typos and mistakes. I am grateful to Tabitha Myers, who typed several parts of this book. I am thankful for Saber Elaydi who advised and encouraged me to write this book. I am indebted to Nancy Baxter Hastings who consulted me on early prepublished versions of this text and greatly supported me. Thanks to Leah Hontz for helping in forming some exercises.
I would like to express my gratitude for the people at John Wiley & Sons Inc. who worked with me on the development of this text. Special thanks to the Mathematics and Statistics Senior Editor, Susanne Steitz-Filler, and the Senior Editorial Assistant of Mathematics and Statistics, Sari Friedman.