Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Russia And Soviet Union - First and Pioneer Flights - 1926 (July 15-16), Pioneer Flight registered cover Moscow - Rostov-on-Don, franked by three air post surcharges, postmarked on arrival, mostly VF, Est. $200-$250 , Scott #C6-7, C9