Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Russia And Soviet Union - 1937, Airplanes, 50k dark violet and black, vertical pair imperforate between stamps, CTO with full OG (NH), VF and rare, this error exists only used, C.v. $4,500, Est. $2,000-$2,500 , Scott #C73a