"ISLANDFAHRT 1931": 30 a. red/green and 2 kr. brown/green, tied by cds. "REYKJAVIK 30. VI. 31" to registered envelope to Offenbach, endorsed "mit Luftschiff Graf Zeppelin!", green triangular cachet "ISLANDFAHRT 1931" alongside, reverse transit and arrival postmarks "OFFENBACH -4 7. 31.", very fine
