APA (7th ed.) Citation

Ernst Heinkel-Flugzeugwerke & United States. National Advisory Committee for Aeronautics. (1927). The Heinkel commercial airplane H.D. 40. National Advisory Committee for Aeronautics.

Chicago Style (17th ed.) Citation

Ernst Heinkel-Flugzeugwerke and United States. National Advisory Committee for Aeronautics. The Heinkel Commercial Airplane H.D. 40. Washington, [D.C.]: National Advisory Committee for Aeronautics, 1927.

MLA (9th ed.) Citation

Ernst Heinkel-Flugzeugwerke and United States. National Advisory Committee for Aeronautics. The Heinkel Commercial Airplane H.D. 40. National Advisory Committee for Aeronautics, 1927.