Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Soviet Union - 1961, Helicopter over the Kremlin, black surcharge 6k on 60k ultramarine, horizontal pair, right stamp without ''6'' variety of surcharge (positions 19-20 of 80-stamp sheet), full OG, left stamp has somewhat gum foxing in places, right one (error) is completely all right, NH, VF and scarce error, which occurs in a small part of print run only, N. Mandrovski certificate, Est. $1,200-$1,500, Sc. #C98, var