AUSTRIA, 1931, April 21, Rocket Flight (E-Z 9C1a; Hopferwieser FS-09b).

AUSTRIA, 1931, April 21, Registering Rocket Flight (E-Z 9C1a; Hopferwieser FS-09b). Card with 10g Air Post tied by violet three-line handstamp, with second handstamp below the rocket cachet, and a third handstamp on back, usual notation in pencil at bottom, addressed to Graz, signed Schmiedl, very fresh, Very Fine, E-Z catalogue states "total of 79 were flown, but very few exist and are extremely rare", Hopferwieser €2,200