books.google.com - This book eases students into the rigors of university mathematics. The emphasis is on understanding and constructing proofs and writing clear mathematics. The author achieves this by exploring set theory, combinatorics, and number theory, topics that include many fundamental ideas and may not be a part...http://books.google.com/books/about/An_Introduction_to_Mathematical_Reasonin.html?id=ImCSX_gm40oC&utm_source=gb-gplus-shareAn Introduction to Mathematical Reasoning