United States, 1930: April 25, Europe-Pan-American Flight Round Trip from New York to New York. Legal-size cover featuring Zeppelins (C13-C14) and all airmail stamps issued from February 13, 1926.  Included stamps:  Map of the U.S. & two planes set of 3 (Scott # C7-C9). ; Spirit of St. Louis (Scott # C10) ;  Beacon on Sherman Hill (Scott #C11) ;  Winged Globe (Scott #C12) ;  Canceled with multiple New York duplex handstamps on April 25, adorned with German and U.S. flight cachets, small Round Trip cachet, and the green May 31 Lakehurst Zeppelin receiver on the reverse side.   Sieger 64 DI