Tham khảo Northrop_XFT

  1. Skyways: 63. tháng 1 năm 1999. |title= trống hay bị thiếu (trợ giúp)
  2. Francillion 1979, p.176.
  • Angelucci, Enzo and Peter M. Bowers. The American Fighter: The Definitive Guide to American Fighter Aircraft From 1917 to the Present, New York: Orion Books, 1987, ISBN 0-517-56588-9.
  • Francillion, René J. McDonnell Douglas Aircraft since 1920. London:Putnam, 1979. ISBN 0-370-00050-1.
  • Green, William and Swanborough, Gordon. The Complete Book of Fighters. New York: Smithmark, 1994. ISBN 0-8317-3939-8.