Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Switzerland - 1936, Disarmament Conference, vermilion (error) surcharge 40c on 90c deep blue and gray, neat cancellation at the corner, VF and rare used, expertized by W. Liniger, C.v. $800, Zumstein #PA24a, C.v. CHF950=US$1,200, Est. $400-$500, Scott #C25a