1922, red Airplane overprint on 45r green and black, left margin horizontal gutter block of four, perfect quality in every respect, full OG, NH, VF and scarce positional piece, Est. $500-$600 (Image)

1927, First International Air Post Conference in the Hague, 10k dark blue and yellow brown, a white spot over ''7'' in ''1927'' variety at right (position 26), full OG, LH, VF, Est. $100-$150 (Image)

1931, Airships, 10k-1r, imperforated complete set of five, nice margins all around, full OG, NH (20k is VLH), VF, G. Biondi certificate, C.v. $350, Est. $100-$150 (Image)

1931, Airship over the Arctic Region, 50k dark gray blue, error of color, full OG, NH, F/VF centering, C.v. $900, Est. $500-$600 (Image)

1931, Ice-Breaker ''Malygin'' and Dirigible ''LZ-127'', 30k-2r, imperforated and perforated (L12½) complete sets of four, the last one is centered well above average, full OG, NH, VF, G. Biondi certificates for each set, C.v. $552, Est. $250-$300 (Image)

1934, Civil Aviation, 5k-80k, complete set of five, printed on paper without watermark, nice and post office fresh, full OG, NH, VF, C.v. $530, Est. $300-$400 (Image)

1935, Airships, 10k-30k, complete set of five, nicely centered and very fresh, full OG, NH, VF, each stamp with neat expert's sign, C.v. $1,020, Est. $500-$600 (Image)

1935, Chelyuskin Rescue, 1k-50k, complete set of ten, perfect unit in every respect, full OG, NH, VF and rare in such quality, C.v. $2,058, Est. $1,500-$2,000 (Image)

1935, Moscow-San Francisco Flight, red surcharge 1r on 10k dark brown, position 3 of 25-stamp setting, well centered, full OG, NH, VF, Z. Mikulski and Soviet Philatelic guarantees, C.v. $1,275, Est. $600-$800 (Image)

1935, Moscow-San Francisco Flight, red surcharge 1r on 10k dark brown, right sheet margin single from position 25 of 25-stamp setting, full OG, NH, VF and rare marginal stamp, Soviet Philatelic guarantee hs, C.v. $1,275++, Est. $1,200-$1,500 (Image)

1935, Moscow-San Francisco Flight, red surcharge 1r on 10k dark brown, small Cyrillic ''f'' in ''Francisco'' variety, position 9 of 25-stamp setting, full OG, LH, VF, Soviet Philatelic guarantee hs, C.v. $1,500, Est. $600-$800 (Image)

1937, Aviation Exhibition, souvenir sheet of four stamps 1r black, buff and red brown, size 165x90mm, fresh condition, full OG, NH, VF, C.v. $450, Est. $150-$200 (Image)

1955, North Pole to Moscow Flight, strongly shifted to the left red overprint on 2r black and yellow green, horizontal pair with perforation L12½ instead of comb 12x12½, full OG, NH, VF, Est. $150-$200 (Image)

1955, North Pole to Moscow Flight, red overprint on 2r black and yellow green, horizontal pair, left stamp with wide space between ''Sev.'' and ''Polus'' (length 15mm), right one without dash variety, full OG, NH, VF and scarce, Soviet Philatelic guarantees on reverse, Est. $300-$400 (Image)

Air Post Official stamps. 1922, red surcharge 600m on Consular stamp of 3r black green on rose and green network, vertical pair of types I and II from positions 6 and 11 of 25-stamp setting, full OG, top stamp is hinged, bottom one - NH, VF and scarce in pair, expertized by Z. Mikulski, C.v. $700 as singles, Est. $400-$500 (Image)

Air Post Official stamps. 1922, red surcharge 1200m on Consular stamp of 2.25r dark blue on green and buff network, position 6 of 25- stamp setting, full OG, NH, VF, A. Diena and Soviet Philatelic guarantees, C.v. $2,200, Est. $800-$1,200 (Image)