1921, Referendum fund for Upper Silesia 2 marka on 25 fen, block of four, with additional franking, tied by cds. “WILNO 21 5 21” to front and reverse of registered cover to Bern with arrival mark “BERN 1.VI.21” and green label “Unbelannt. Unconnu….”, and additional two-line “ERFOLGLOS AUSGERUFEN..”, thus returned with arrival mark “WILNO -7 6 21”, including the registration slip, fine and attractive
