Elementary Go: Volume 4: v. 4

The approach to life-and-death problems used in this book is to emphasize the status of standard groups. Most life-and-death problems in books are presented in the following manner: Black to play and kill; or White to play and live; or Black to play and live in ko; etc. This format has the advantage that even without looking at the answer, you usually know when you have solved the problem. Unfortunately, during a game there is no one standing at your elbow to tell you that this group can be killed or that one can be saved in ko, etc. In actual play you have to work out the status of each group that comes into question. I believe that this way of presenting problems will help many players to win games.