Souvenir sheet issue "east European postage stamps exhibition, OSTROPA, Konigsberg", original size, cancelled by special cancel "Konigsberg (Pr) Ostropa, Int. Postal stamps exhibition from 23. June - 3 July 1935, 25.6.35", very fine, unsigned, photo expertize Andreas Schlegel BPP (2025) "the quality is perfect. ", Michel 1.100.-