Haengma The Book

행마 (ISBN 89-333-0346-4). Haengma is a Korean problem book that is divided into three classes.

The Lower Class and the Middle Class both consist of problems involving corner sequences, specifically jeongseok variations and continuations. Each problem is black to move and is presented on a single page with a bit of an explanation with three solutions presented on the back. The first solution is always the correct one, and the other two diagrams can present other correct solutions, continuations, or wrong answers (generally with comments to the effect of "white is thick" or "white settles himself easily in the captions).

The Upper Class consists of whole board problems--some with lettered options, some without--and can be either white or black to move. The solution page consists of a correct solution and an incorrect solution (marked "failure" in the caption).