cover 1931 Graf Zeppelin North Pole Flight covers (2), one bearing 1931 (15 July) imperf. 30K. to 2r. set of four, the other with similar 30K. vertical pair and 2r. single; both covers cancelled in Leningrad and bear "Polarfahrt" cachets and Ice-Breaker "Malyguin" d.s. (27.7). Fine