Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Poland - Gordon Bennett Balloon Post - 1935-36, three postcards, including two posted to Flight on September 15, 1935, originated from France and Switzerland, and one - to Flight on August 30, 1936, originated from France, all delivered to Soviet Union, flight of 1935 to Veshenskaya (Azov-Chernomorsk Krai, now Rostov Obl.), both uprated by definitive stamp of 4k claret, flight of 1936 to Arkhangelsk (North Krai), each one with confirmation cachet and appropriate markings, mostly VF, Est. $300-$400