cover Switzerland, Zeppelin flight card, 1924, single 25c Dark Blue and Blue (C5) tied by Luzern c.d.s. in mixed franking with Germany 50pf Orange (C23), tied by Friedrichshafen c.d.s. on Zeppelin flight card with printed address to the U.S. (Sieger 20), the 1924 American Flight of the Z.R.3 (also known as LZ126), violet Z.R.3 oval flight cachet, very fine