"'Pin-pointing.' U.S. School of Aerial Photography, Langley Field, Virginia (photo courtesy of U.S. Air Force)", from Grover Heiman, The Story of Aerial Photography, page 53. National Archives, photo no. 165-WW-456E-5.
“I Spy With My Glass Eye”: Aerial Photography and Innovation in World War I
U.S. Air Force
McMaster University Libraries book collection
McMaster University Libraries
Copyright, public domain. McMaster University owns the rights to the archival copy of the digital image in TIFF format. "reproduced from Aerial Photography: the Story of Aerial Mapping and Reconnaissance (Macmillan)"