GROUP OF 12 AIR POST ISSUES: 1921-33, Bleriot XI first and second sets, Semi-Postal Air Post sets - Eagle, Aviation Pioneers and two imperforated sets of Biplane with upright and sideways watermark, full OG (three stamps with toned gum), NH, VF, C.v. $925, Est. $250-$300 (Image)

1928 (May 10-11), Deruluft Flight cover from Riga to Moscow, franked by ''Bleriot IX'' complete set of three triangle stamps and Arms stamp of 5s on reverse, Deruluft bilingual confirmation marking and arrival ds on reverse, mostly VF, Est. $100-$150 (Image)