1924-26, two registered covers franked by ''Fokker F111'' surcharged issues with additional franking, first one from Moscow to New York via Berlin, the other one from Kharkov to London via Moscow and Berlin, all appropriate markings and arrival ds, F/VF, each one with I. Kirzhner certificate, Est. $100-$150 (Image)

1928 (May 15), Pioneer Flight registered cover from Moscow to Germany, franked by four stamps, including two of the Hague Air Post Conference 15k in horizontal pair, Berlin Luftpostamt boxed marking and ''15.5.28'' arrival ds, mostly VF, Est. $120-$150 (Image)

1931, Airship Constructions, 10k-1r, complete set of five, all with perforation L12½, full OG, NH, mainly VF, C.v. $300, Est. $200-$240 (Image)

1932 (August 26), Attempt of Flight Franz Josef Land to Arkhangelsk, card and cover franked by International Polar Year stamps of 50k and 1r respectively, both addressed to Vienna with Berlin transit postmarks, mostly VF, Est. $150-$200 (Image)

1932 (August 26), Attempt of Flight Franz Josef Land to Arkhangelsk, cover franked by International Polar Year stamps of 50k and 1r, complete set of two, addressed to Moscow with arrival ds on reverse, VF, Est. $150-$200 (Image)

1932 (August 29), International Polar Year, 50k carmine (perf 12) and 1r green (perf 10½), complete set of two used on registered air mail cover from Moscow to USA via Berlin, transit and arrival markings on reverse, VF and scarce complete set franking of non-Polar cover, Est. $250-$300 (Image)

1933, ''Stratostat USSR 1'', 5k, 10k and 20k, three covers franked by these stamps, the first one sent from Moscow to Stalingrad, second one - locally sent in Moscow, the last one - from Baku to Kashira (Moscow Obl.), mainly VF, Est. $300-$400 (Image)

1935 (January 31-February 4), Airships, 5k-30k, complete set of five, used on registered air mail cover from Moscow to Boebling, all appropriate marking and arrival ds, mostly VF and rare, usually this set was used on Zeppelin postcard, Est. $600-$800 (Image)

1935, Moscow-San Francisco Flight, red surcharge 1r on 10k dark brown, position 2 of 25-stamp setting, very well centered, full OG, LH, VF, Soviet Philatelic guarantee, L. Hovest certificate, C.v. $500, Est. $400-$500 (Image)

1935, Moscow-San Francisco Flight, red surcharge 1r on 10k dark brown, position 25 of 25-stamp setting, full original slightly disturbed gum with very slight foxing, VF, Soviet Philatelic and several other guarantees, C.v. $500, Est. $400-$500 (Image)

1938, 2nd Trans-Polar Flight, 20k gray black, imperforated single with enlarged margin at bottom and nice margins at other sides, typical gum wrinkles, full OG, NH, VF, C.v. $950, Est. $400-$500 (Image)

1961, Helicopter over the Kremlin, black surcharge 6k on 60k ultramarine, horizontal pair, right stamp without ''6'' variety of surcharge (positions 19-20 of 80-stamp sheet), full OG, left stamp has somewhat gum foxing in places, right one (error) is completely all right, NH, VF and scarce error, which occurs in a small part of print run only, N. Mandrovski certificate, Est. $1,200-$1,500 (Image)

NORTH POLE FLIGHTS AND RELATED ITEMS: 1938-61, 12 mainly illustrated covers, representing registered cover from Leningrad to NYC of 1938, cancellations of North Pole Stations No.7, 8 and 9, North Pole souvenir sheet on registered cover to Vienna and etc., fresh quality, VF, Est. $300-$400 (Image)