The book, North American XB-70 Valkyrie represents a authoritative pictorial study of the experimental XB-70 supersonic bomber.  The XB-70 came from the United States Air Force's interest in the 1950s of developing a chemical or nuclear propelled supersonic strategic bomber to replace the Boeing B-52 by 1965.  Various proposals were reviewed but in the end the one submitted by North American Avaition was selected by the United States Air Force.  As the selection process was developing, the United States Air Force requirements were evolving such that the idea of chemically powered aircraft ended in 1956 and by 1961 nuclear-powered aircraft met the same fate.  Despite these major changes to the requirements for a new strategic bomber, the XB-70A design survived these changes but strictly as an experimental program.  The XB-70A program lead to the construction of two aircraft: 1) XB-71A-1 (first flight on September 21, 1964) and 2) XB-70A-2 (first flight on July 17, 1965).  The flight test program continued into 1968 where the 82nd and last flight was recorded.  Unfortunately, the second XB-70A was hit by one of its chase aircraft on June 8, 1966, which resulted in the deaths of two pilots and the total destruction of both aircraft.  As NASA completed its final supersonic test flight of the first XB-70, a decision was made to fly the aircraft to Wright-Patterson AFB museum near Dayton, Ohio where it was put on public display.  The major sections of "North American XB-70 Valkrie" are as follows: 1) Acknowledgements; 2) Introduction; 3) Chapter-1 Development; 4) Chapter-2 Flight Test; 5) Chapter-3 XB-70 Accident and 6) Chapter-4 XB-70 In Detail.  In addition to an informative narrative, "North American XB-70 Valkyrie" includes the following features: 1) Approximately 95 black and white photographs; 2) 2 black and white illustrations and 3) 1 three-view XB-70 A-1 black and white illustration.  This book is 48 pages and is in very good condition.  The author is John M. Campbell with Garry R. Pape.  Edition published in 1996.