Bell, Dana (1995)       Air Force Colors Volume 1 1926-1942, Carrollton:  Squadron Signal Publications  ISBN:  0-89747-316-7. 
according to Section 40.1.1.2 Color of MIL-STD-2161A (AS), the colors of this insignia are established as FED-STD-595 red 11136 white 17925 blue 15044. The visualization of the colors comes from http://www.colorserver.net/showcolor.asp?fs=11136+17925+)

 Elliot, John M. (1989)       The Official Monogram US Navy &amp; Marine Corps Aircraft Color Guide Vol 2 1940-1949, Sturbridge, MA:  Monogram Aviation Publications  ISBN:  0-914144-32-4.
USAAS SPAD S.XIII