John Thomas Farquhar, A Need to Know: The Role of Air Force Reconnaissance in War Planning, 1945–1953 (Maxwell Air Force Base, Alabama: Air University Press, February 2004), 8.
Dr. Alfred Price, Targeting the Reich: Allied Photographic Reconnaissance Over Europe, 1939-45, (London, Greenhill Books, 2003), 9.
J.Rickard, “Photo Reconnaissance Spitfires,” historyofwar.org, n.d. Web 15 May 2012 http:// www.historyofwar.org/articles/weapons_spitfire_PR.html