" Winkler's book will certainly appeal to the mathematician, as well as to students of all ages--high-school, college, and graduate. His philosophy of what constitutes a good puzzle is right on the mark, showing that this Connoisseur's Collection really is of quality and depth. -James Tanton, MAA Online, September 2004 "I have gained great satisfaction from those [puzzles] I've managed to solve ... This is a great collection of seriously hard questions." -The Mathematical Gazette, March 2006 "As an enthusiastic solver and collector of mathematical puzzles myself, I was absolutely delighted with this book. The sheer density of mathematical ideas and challenges sets it apart from other books of a similar nature while the lucid yet informal style of exposition makes the journey from ignorance to enlightenment enjoyable." -Norman Do, The Australian Mathematical Society Gazette, July 2004"