Luxembourg: 1936, 1. North America flight, handing in for transport Frankfurt with confirmation stamp "c", registered cover from LUXEMBOURG 29.4. With pair 1 3 / 4 Fr. Airmail and D. Reich 50 Pfg. And 75 Pfg. Zeppelin with postmark FRANKFURT 2.5. To the United States, 50 Pfg. Value round corner and slightly blotched, otherwise superb