Auction #93 Worldwide Air Post stamps and postal history, Zeppelin Flight items, philatelic rarities of the World

1919, black monogram error surcharge 50r on 5r dark blue, green and light blue, paired with a common 100r on 5r, two perforated singles, full OG, NH, VF, error stamp with Cyrillic ''Z.U.'' (Zakhary Umikov) hs is not listed in the Artar Cat., Est. $150-$200