Zeppelin Flight covers. April 23-24, 1929, Zeppelin Mediterranean Sea Flight postcard to Vienna, franked by four air post stamps, Friedrichshafen dispatch, red confirmation cachet, Seville ''24.ABR.29'' machine dropped marking on reverse, VF, Mi #20 II, €350 (Image)

Zeppelin Flight covers. July 12, 1931, Zeppelin Austria Flight cover to Vienna, franked by three adhesives, including ''Airplane and Crane'' stamp of 3s red brown, Friedrichshafen dispatch, blue flight cachet and arrival ds, VF, Sieger #116A, €225 without premium for franking (Image)