Avianca. 1950-51 "A" Overprints, mint and used selection with varieties including inverted and double overprints, multiples with and without overprint, 1951 set of eight with overprint omitted, also 1950 set mint, 1951 2p and 5p large sunken die proofs in the issued colours without overprint, etc., several with A.P.S Certificates. (40).