Influence( The Psychology of Persuasion) is an amazing book. I was reading this book at the bookstore and I was astonished to noticed the simple principle of psychology of persuasion can make little difference in dealing with others. But, once we realize the importance of persuasion and understanding the psychology of humans--then it becomes an easier process to influence other people. Because, implementing the practice of psychology of persuasion would have a better impact in relationship with others such as friends, colleagues, spouses, customers and new associates.
http://www.influenceatwork.com/( Robert Beno Cialdini is the Regents' Professor Emeritus of Psychology and Marketing at Arizona State University and was a visiting professor of marketing, business and psychology at Stanford University)