Worldwide Stamps and Covers.

1937 (28 July) World Record Non-stop Transatlantic flight, Moscow-San Jacinto, by Soviet aviators Mikhail Gromov, Danilin and Andre Yumashev on their long-distance record flight via the North Pole. The airplane was a single-engine ANT-25-1 which flew 6262 miles in 62 hours and 17 minutes, beautifully illustrated cover signed by two crew-members, also by Sir Hubert Wilkins, v.f. (no official mail was carried on the flight)
Estimate: $150