Chess Problems By World Champions
Kenn E. Thompson & Dwight K. Weaver
This book can be downloaded and read in iBooks on your Mac or iOS device.
This book presents the reader with chess problems taken from the games of players who became World Champions (unofficial, and official). Some of these problems are easy to solve while others are almost impossible to solve. The solutions range from mate in 2 moves to mate in 17 moves.
Really great value and instructional
This book is a steal for what it costs. It has a ton of chess problems and they range in difficulty, getting harder as the book goes on. This really helped me see the board clearer.