Air Post stamps and covers. 1933 (May 28), two Latvia - Africa stamps, including 15s and the ''key'' 100s on 25s, used on air mail cover from Riga to Paris, appropriate cancellations and Par Avion label, no backstamp as always exists on ordinary mail, VF and rare franking, expertized by A. Rucins, P. Zarins certificate, Est. $500-$600 (Image)