Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Soviet Union - 1977, History of Aviation, 4k-20k, complete set of six die proofs in gray black, artist E. Aniskin, engravers M. Silyanova and V. Smirnov, approximate size 120x100mm, each one with side printer's markings, produced on gummed paper with hinge traces, VF and extremely rare, especially in complete set, Est. $3,000-$4,000, Scott #C109-14