1931 Moscow - Stuttgard flight on registered airmail cover canc. "MOCKBA*13.7.31", via "BERLIN*14.7.31", arr. "STUTTGARD*15.7.31". Cover fr. with 1931 Zeppelin USSR issue, complete set of 5 values imperforate (Mi. 397CX/401CY-300E). Cachet "MIT LUFTPOST BEFORDERT/LUFTPOSTAMT/BERLIN C.2".