1912 (February 17), Emeryville Race Track Aviation Meet, stationery postcard 1c blue, addressed to Selma, CA, tied by ''Aeroplane Station Oakland Cal. Feb. 17, 1912'' machine ds (flown on the first day of the Meet), fresh and VF, AAMC #16, Est. $200-$300 (Image)

1931 (May-September), North Pole Flights of Wilkins - Ellsworth Trans-Arctic Submarine Expedition, three-country franking cover from New York to Dayton, OH via London, North Pole, Leningrad and New York, bearing Beacon 5c carmine and blue, uprated by GB King George V stamp of 1½p yellow brown and imperforated single of Soviet Ice-Breaker ''Malygin'' 35k green (on reverse), confirmation and other appropriate markings with arrival ds on reverse, VF, Est. $250-$300 (Image)

1931 (June 19), Trans-Atlantic Flight by O. Hillig and H. Hoiriis pre-printed cover, franked by US Red Cross 2c black and red, due to technical difficulties flight was interrupted at Harbor Grace (Newfoundland) and correspondences were delivered by a ship, upon arrival to Denmark uprated by 25ø light blue and postmarked ''3.7.31'' in Copenhagen, VF, only 30 items carried, Est. $150-$200 (Image)

1931 (July 15-19), Justice for Hungary Non-Stop Trans- Atlantic Record Flight by Alexander Magyar and George Endresz, specially printed postcard, franked by 1c green, upon arrival Hungarian postage due of 32f carmine rose was applied, No. 0094 at top left, all appropriate postal and confirmation markings, VF, Mueller #31, 7,500 points, Est. $200-$250 (Image)

1933 (July 24), Balbo Air Squadron Flight, New York- Rome, cover addressed to Germany, franked by five stamps, including three high value definitives, tied by ''New York Varick St. Jul.24'' duplex, violet ''Italian Air Cruise'' confirmation cachet, blue No.2217 at bottom left, Grociera Aerea Rome drop and Wesseling (Köln district) arrival ds, mostly VF, AAMC #1184f, Est. $500- $600 (Image)

1934 (June 27-July 2), Benjamin and Joseph Adamowicz Trans-Atlantic Flight from New York to Warsaw cover with pre-printed flight itinerary, franked by Washington 2c carmine, upon arrival to Warsaw uprated by Polish air post stamp, signed by both brother-pilots at top, Warsaw ''2.VII.34'' arrival ds, VF, Est. $200-$250 (Image)

1895, Webster, 10c dark green, bottom sheet margin with imprint and plate No.62 horizontal strip of three, full OG somewhat disturbed on margin, NH, fine, C.v. $1,000, Est. $250-$300 (Image)

1895, Marshall, $5 dark green, watermark USPS, fresh color and intact perforation, full original slightly disturbed gum, previously hinged, close to VF centering, PF certificate, C.v. $2,000, Est. $400-$500 (Image)

1895, Marshall, $5 dark green, watermark ''USPS'', neat purple Specimen overprint at the top left, no gum, F/VF, C.v. $400, Est. $150-$200 (Image)

1909, Washington, $1 violet brown, a single with bottom margin plate No.4957, full OG, NH, PF certificate graded F/VF 75, C.v. $1,050, Est. $350-$400 (Image)

1917, Washington, 2c carmine, type I, horizontal pair imperforated vertically, usual centering, full OG, previously hinged, PF certificate for block of four, this one being the top pair, C.v. $550, Est. $250-$300 (Image)

1918, Franklin, $5 deep green and black, right arrow block of four, rich colors, full OG, NH, F/VF, C.v. $1,360 as four singles, Est. $500-$600 (Image)

1919, Washington, 1c gray green, horizontal pair imperforated vertically with straight edge at right as always exists, fresh color, full OG, NH, fine and rare, C.v. $1,400, Est. $750-$1,000 (Image)

1919, Washington, 2c carmine rose, type III, block of four imperforated horizontally, full OG, NH, F/VF, C.v. $275, Est. $120-$180 (Image)

1922, Franklin, large die proof of 2c in deep green on India paper, mounted on large card, proof size 73x87mm, card size 147x192mm, endorsed by John H. Bartlett, Postmaster General at the bottom, reversal No. 1181454, light traces of hinges, fresh and VF, C.v. $1,000, Est. $500-$800 (Image)

1931, regular issue of rotary press printing, 11c-50c, complete set of ten, perforation 11x10½ or 10½x11, very-well centered blocks of four, full OG, NH, VF/XF, C.v. $549 as singles, Est. $250-$300 (Image)

1943, Flag of Czechoslovakia, 5c blue violet, blue, red and black, double impression of ''Czechoslovakia'', full OG, NH, VF, a copy of PF certificate for block of 20, stamp position identified, C.v. $600, Est. $200-$300 (Image)

1943, Flag of Austria, 5c blue violet, red and black, right sheet margin horizontal strip of three, middle stamp with double impression of ''Austria'', full OG, NH, VF, PSE certificate for block of six, this strip being at bottom, C.v. $400++, Est. $200-$250 (Image)

1966, 25th Anniversary of the US Savings Bonds, 5c red, dark blue, light blue and black, left sheet margin block of four, top right stamp has missing dark blue color due to foldover, full OG, NH, VF and extremely rare, Datz mentioned at lest two such errors are known, C.v. $5,000, Est. $2,500-$3,000 (Image)

1968, Walt Disney, (6c) multicolored, right sheet margin single with ocher omitted (Walt Disney, 6c and etc.), full OG, NH, VF, C.v. $300, Datz C.v. $350, Est. $150-$200 (Image)

1968, Walt Disney, 6c multicolored, a single with black omitted (United States and etc.), full OG, NH, VF and rare, a common stamp is included for comparison, according to Datz 35 error stamps known, C.v. $1,750, Est. $800-$1,000 (Image)

1968, Waterfowl Conservation, 6c multicolored, left sheet margin block of four, imperforated horizontally between stamps, full OG, NH, VF, C.v. $500 as two pairs, Est. $300 -$400 (Image)

1968, Waterfowl Conservation, 6c multicolored, right sheet margin single with red and blue omitted, full OG, NH, VF, C.v. $350, Est. $150-$200 (Image)

1969, Folklore issue, (6c) multicolored, a single with black and Prussian blue colors omitted, full OG, NH, VF, C.v. $400, Est. $150-$200 (Image)

1970, Christmas issue, 6c multicolored, side margin horizontal transition strip of ten, representing three stamps on the left with completely omitted black offset color, 4th stamp at left has omitted it partially, full OG, NH, VF and scarce, especially in transition strip, C.v. $1,200+ +, Est. $500-$600 (Image)