The Ulyasutai Advertising Cover, an amazing new discovery

Marcus Orsi, Chief Philatelist presents the Ulyasutai Advertising Cover which will be auctioned on December 4 in Geneva in our 18th Rarities of the World Auction:

https://www.davidfeldman.com/buying/auctions/browse-lots/aucP/2014-december-auction-series/item/258134/