Flag for the Chief of a "Luftflotte", Deutsches Reich, 1937-1940
Own work, also source pages 70 and 71 from

Jean, Denis; Lepage, G. G. (2009)       Aircraft of the Luftwaffe 1935–1945: An Illustrated History, McFarland &amp; Company, p. 402  ISBN:  0786439378.
Fornax