Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Argentina - 1950, International Philatelic Exhibition, 10+10c - 5+5p, complete set of six imperforate trial color proofs in blocks of four, printed on thick wove paper, no gum as issued, NH, VF, Est. $300-$350 , Scott #CB1-5, B12