Positional Pieces. July 13-14, 1928, Pioneer Flight Hanover - Furth/Nuernberg specially printed postcard, posted at Wangerooge, franked by Immanuel Kant 15pf vermilion, a single with ''X'' label at left, red confirmation marking is alongside, VF and scarce franking, Mi #W23, C.v. €400 for used stamp on postal history item w/o a premium for flight card, Est. $120-$150 (Image)