S23659

South America Flight 1931 - ppc with high valuable Switzerland airmail stamps mixed franking and sent by registered mail (this option was 1st time accepted at this flight), cancelled Romanshorn 16.X.31 sent via Friedrichshafen and carried by airship on it' s third South America Flight with Buenos Aires arrival postmark, very good quality, Sieger 133 o CH, Michel Zeppelin specialized catalogue 229 a CH