Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Danzig - Zeppelin Flight - 1931 (June 28), Schwaben Flight postcard, franked by two stamps, tied by oval date stamp, Friedrichshafen ''28.6.31'' connection and Böblingen the same day arrival marking, violet confirmation cachet, VF, Sieger #112, Scott #C29