United States. National Advisory Committee for Aeronautics. (1939). Wind-tunnel investigation of N. A. C. A. 23021 airfoil with various arrangements of slotted flaps. [s.n.].
Chicago Style (17th ed.) CitationUnited States. National Advisory Committee for Aeronautics. Wind-tunnel Investigation of N. A. C. A. 23021 Airfoil with Various Arrangements of Slotted Flaps. [Washington]: [s.n.], 1939.
MLA (9th ed.) CitationUnited States. National Advisory Committee for Aeronautics. Wind-tunnel Investigation of N. A. C. A. 23021 Airfoil with Various Arrangements of Slotted Flaps. [s.n.], 1939.
Warning: These citations may not always be 100% accurate.