1979. . Swanborough, F. G. and Peter M. Bowers. United States Military aircraft since 1909. London: Putnam, 1963, 1971, 1989. . Further reading External links National Museum of the USAF - A-33 Fact Sheet Douglas 8A-5 for Norway, A-33 1940s United States attack aircraft World War II trainer aircraft of the United States Single-engined tractor aircraft Low-wing aircraft A-33 Aircraft first flown in 1940