1933, A Century of Progress Zeppelin Flight, 50c green, top sheet margin plate No.21177 block of four, full original gum with minor usual waves, NH, VF, C.v. $300 as four singles, Est. $100-$150 (Image)

1938, Eagle with Shield, 6c dark blue and carmine, vertical pair imperforated horizontally, full OG, trace of hinge mark, F/VF, C.v. $300, Est. $150-$200 (Image)

1973, Progress in Electronics, 11c multicolored, a single with vermilion and olive litho colors omitted, full OG, NH, VF, C.v. $700, Est. $300-$400 (Image)

1983, Summer Olympics, 40c x4 multicolored, top left corner sheet margin plate No.2222 imperforated se-tenant block of four, full OG, NH, VF, C.v. $650, Est. $300-$400 (Image)

1985, Trans-Pacific Air Mail, 44c multicolored, top left corner sheet margin vertical imperforated pair, full OG, NH, VF, C.v. $600, Est. $250-$300 (Image)

1989, 20th UPU Congress, Futuristic Mail Delivery, (45c) multicolored, se- tenant block of four with light blue (engraved) color omitted (country name and denomination), full OG, NH, VF, C.v. $500, Est. $250-$300 (Image)

1991, Harriet Quimby, 50c multicolored, bottom margin vertical pair imperforated horizontally, perfect condition, full OG, NH, VF and scarce, C.v. $900, Est. $400-$500 (Image)

Zeppelin Flights. 1925 (May 8-10), Airship Los Angeles Return Flight cover from San Juan to Lakehurst to Cleveland, franked by Franklin 3c green in vertical imperforated pair, red three-line confirmation cachet, postmarked on reverse, F/VF, Sieger #20W, €250, Est. $130-$160 (Image)

Zeppelin Flights. 1930 (June 3-6), 1st Europe - Pan America Round Flight postcard, delivered on legs Lakehurst-Seville, Seville- Friedrichshafen, franked by Zeppelin stamp of 65c green, red German and violet American confirmation markings, Friedrichshafen ''6.6.30'' arrival, the card returned to US by ship on June 18 (green Zeppelin marking is alongside at the bottom), VF, Sieger #64A, Est. $100-$150 (Image)

Zeppelin Flights. 1933 (October 23-November 2), Century of Progress Flight, three US covers on legs Miami - Chicago, Chicago - Friedrichshafen and Akron (second landing) - Friedrichshafen, each one franked by ''Baby'' Zeppelin 50c green, each one with appropriate markings and arrival ds, mostly VF, Est. $150-$200 (Image)