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, 28.6.35", due to the sulphurous gum evenly shaded - very fine, photo expertize Schlegel BPP, Michel 1.100.-