The P-40A designation was skipped
in the initial designation assignments. However, it was applied
retroactively to P-40 Ser No 40-326 when it was converted to
a camera-carrying photographic reconnaissance model at Bolling
Field in March of 1942.
War Planes of the Second World
War, Fighters, Volume Four, William Green, Doubleday, 1964.
The American Fighter, Enzo Anguluci
and Peter Bowers, Orion Books, 1987.
United States Military Aircraft
since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian
Institution Press, 1989.
Curtiss Aircraft, 1907-1947, Peter M. Bowers, Naval Institute
The Curtiss P-40 Tomahawk, Ray Wagner, Aircraft in Profile,
Volume 2, Doubleday, 1965.