Aero Spacelines Guppies. NARA Verlag, Allershausen 1996, . Bowers, Peter M.: Boeing Aircraft since 1916. Putnam Aeronautical Books, London 1989, . Swanborough, Gordon and Bowers, Peter M.: United States Military Aircraft since 1909. Putnam Aeronautical Books, London 1989, . External links KC-97 page at the National Museum of the United States Air Force Airworthy KC-97 Angel of Deliverance KC-097 KC-97 Stratotanker Four-engined tractor aircraft Low-wing aircraft Aircraft with auxiliary jet engines Air refueling Stratotanker Four-engined piston aircraft