Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Liberia - 1938, Airplanes and Birds, imperforate plate proofs of 1c-$1, set of ten in pairs, each stamp with ''Proof'' overprint in black, less 20c (not issued as such), but including two of 4c in orange (issued color) and yellow, perfect condition, full OG, NH, VF and rare, Est. $400-$500, Scott #C4/13