U.S. & Worldwide Stamps & Postal History

1931 50k gray blue (error), used in combination with additional 80k franking on registered cover from Kharkov (4.12.40) to Germany, redirected on arrival from Soltau to Heligoland, with transit and arrival markings, censored and resealed by German Wehrmacht label on back, fine and extraordinary usage of the celebrated "Ospitka" color error on cover to the Third Reich (six months later Germany invaded the Soviet Union)
Estimate: $5000