1931, Airship over Kremlin, 20k dark carmine, four-side margins imperforated single with vertical position of watermark Borders and Rosettes, full OG, NH, VF and scarce watermark variety, Est. $150-$200 (Image)

1931, Airship Constructions, 10k-1r, complete set of five, all with perforation L12 1/2, full OG, NH, mainly VF, Est. $200-$250 (Image)

1931, Airship over the Arctic Region, 50k dark gray blue, error of color, nicely centered, full OG with tiny gum wrinkle, which is not really important, NH, VF, C.v. $900, Est. $400-$500 (Image)

1931, Airship over the Arctic Region, 50k dark gray blue, error of color on thinned (no more then 0.075mm) paper, left sheet margin single, full OG, NH, VF (LH on selvage) and very scarce, Est. $500-$700 (Image)

1932, Airship over the Dnieper Dam, 15k gray black, engraved printing, perforation 10 1/2, nicely centered for this difficult stamp, full OG, light trace of hinge, VF, this stamp has been sold at Cherrystone Auction in May 2012, lot #2502, for $1,500 plus appropriate fees, Est. $1,200- $1,500 (Image)

1932, Airship over the Dnieper Dam, 15k gray black, engraved printing, enlarged margin at top with nice margins at other sides, full OG, previously hinged, VF and very scarce stamp of only 100 printed, several expert's hs on reverse, Est. $2,000- $2,500 (Image)

1935, Special delivery registered cover from Kharkov to Mannheim, franked by five commemorative stamps, including Airship over the Dnieper Dam 15k gray, engraved stamp with perforation 14, which is very scarce, all appropriate markings and arrival ds on reverse, VF, Est. $300-$400 (Image)