Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Belgium - 1931 (October 16), Air Post Exhibition in Antwerp, four Air Post covers sent from Exhibition to Paris, London, Amsterdam and Malmö, each one bearing specially overprinted for each city semi-official stamp of 50c blue along with appropriate franking, confirmation markings, labels and arrival ds, VF, Est. $250-$300, Sc. #C1-2