Book excerpt: Textbooks of Military Medicine. Specialty editors: Kent B. Pandoff and Robert E. Burr. Volume two in the three-volume textbook, "Medical Aspects of Harsh Environments," which provides historical information, proper prevention and clinical treatment of the various environmental illnesses and injuries, and the performance consequences warfighters face when exposed to environmental extremes. This volume deals with the effects of altitute, especially as experienced in mountain terrain and by aviators, and the complex interactions between humans and the special environments created by the machines used in warfare. Index included.