Apostolo, Giorgio. The Illustrated Encyclopedia of Helicopters. New York: Bonanza Books. 1984. . Donald, David. "Sikorsky S-67, S-69 and S-72".The Complete Encyclopedia of World Aircraft. New York: Barnes & Noble Books, 1998. . Great Britain. Sikorsky S-67 Blackhawk N671SA: Report on the Accident at Farnborough, Hampshire, England on 1 September 1974. Aircraft accident report, 1/76. London: H.M.S.O., 1976. . Landis, Tony and Dennis R. Jenkins. Lockheed AH-56A Cheyenne. Warbird tech series, v. 27. North Branch, MN: Specialty Press Publishers and Wholesalers, 2000. . Yamakawa, George M., Albert L. Winn, Raymon B. Smith, Roy J. Anderson, Jr., and Warren E. Griffith, II. Attack Helicopter Evaluation, Blackhawk S-67 Helicopter. Ft. Belvoir: Defense Technical Information Center, July 1972. Retrieved on 22 December 2010. External links Sikorsky S-67, First Blackhawk on helis.com United States military helicopters S-067 1970s United States attack aircraft 1970s United States helicopters Twin-turbine helicopters Aircraft first flown in 1970 Attack helicopters Cancelled military aircraft projects of the United States