Souvenir sheet issue "east European postage stamps exhibition, OSTROPA, Königsberg", original format, cancelled by special cancel "Königsberg (Pr) Ostropa, Int. Postal stamps exhibition from 23. June - 34 July 1935, 23.6.35" (first day), faultless condition, unsigned, photo expertize Hans Dieter Schlegel BPP (2024) "the quality is perfect. ", Michel 1.100.-