United States. Army Air Forces. Air Force, 2nd. Altitude Indoctrination Unit
A source of general reference concerning oxygen equipment and its use by members of crews flying the B-17, B-24 heavy bomber, and the B-29 combat bomber. The subject matter is presented from a practical point of view, based upon actual experiences encountered on altitude missions.
These books are free to read. Each is in the public domain in the United States; check your own country's rules before you copy or share one.