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Valverde, Horace H. (July 1968). "Flight Simulators: A Review of the Research and Development"(PDF). Defense Technical Information Center. Wright-Patterson Air Force Base, Ohio: Aerospace Medical Research Laboratory, Aerospace Medical Division, Air Force Systems Command. pp. 136, 138–139. Archived from the original(PDF) on July 14, 2019. Retrieved 12 June 2020.