souvenir sheet issue "east European postage stamps exhibition, OSTROPA, Koenigsberg", original size, cancelled by special cancel "Koenigsberg (Pr) Ostropa, Int. postal stamps exhibition from 23. June - 3 July 1935, 27.6.35", very fine, unsigned, photo expertize Andreas Schlegel BPP (2025) "the quality is perfect. ", Michel 1.100.-