1927, carmine Airplane surcharge 1L on 6L deep blue and pale lemon, horizontal pair imperforate between stamps, full OG, NH, VF and rare, Sanabria #1c, priced with "..."

250.00

1929 (October 16), Zeppelin 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. $300-$350

150.00

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. $200-$250

100.00