Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Best book on the subject!!!

Helmut Reichmann's book is still by far the best book on the subject of cross country soaring. It has helped me - and a lot of other glider pilots - a great lot. It may be a little outdated on the subject of electronic final glide computers and the like, but by far the rest of it is still indispensible - and fun! - reading.Helmut died a few years ago in a soaring accident.