1932 (May 14), Strasbourg Exhibition Flight cover from Sofia, addressed to Paris, franked by Rila Monastery complete set of three, tied by red special Sofia date stamps, part of postal receipts seal and Paris "23.V.32" arrival marking, mostly VF, Est. $100-$150

100.00

1929 (October 16), Balkan and Silesia Flight cover from Sofia to Pforzheim, franked by 6L dark blue and pale lemon, tied by Sofia date stamp, the same day Zeppelin onboard marking, four-line cachet on reverse, mostly VF, Sieger #42-43 var, Est. $400-$500

200.00