Helmut Reichmann was a very competitive sailplane racer and a strong mathematician. This book explains the complicated speed-to-fly theories and backs them with many equations that can be used to model cross-country soaring flight. I especially like the sections on how and where thermals form, competition tactics, and speed-to-fly theory.
Sections
Part I
Flight in Lift
Navigation
Landing Out
Speed-to-Fly
Physical Conditioning
Competition Tactics
Training and Conditioning
Equipment

Part II
Meteorology
Speed-to-Fly
Equipment