Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - RSFSR and Soviet Union - Pioneer Flight - 1931, Ice-Breaker ''Malygin'' and Graf Zeppelin, 30k-2r, perforated (L12½) complete set of four used on registered air post cover from Moscow to Germany on March 7, 1933, Berlin Luftpostamt marking, transit and arrival ds on reverse, VF and scarce complete set franking, Est. $600-$700, Scott #C30a-33a