Switzerland : Stamps [30th Anniv. of First Flight over the Alps by Oskar Bider | Year: 1943 | Overprint Variant: 22119 | Perforation: comb 11¾] : Colnect 📮
MiNr. CH 421 with changed face value and black overprint. This stamp could be used only for the special postal flight across the Alps by the Swiss aviator Oskar Bider, from Zürich to Bern in both directions.
