1934, ''Portugal'', ½a-20a, set of ten imperforated plate proofs in horizontal pairs, printed on paper with watermark ''Maltese Cross'', no gum as produced, NH, VF and scarce unit (Image)

Air Post stamps. 1936, ''Portugal'', black overprints or surcharge ''Aviao'', complete set in sheet margin blocks of four, dried original gum as always exists, NH, VF, C.v. $230 as hinged singles (Image)

Air Post stamps. 1940, New York World's Fair, green overprint on 50a red brown, two singles, one of which has inverted overprint, full OG, NH, VF, 2,000 stamps were issued with a common overprint, and only 25 were produced with inverted one, made this stamp an undoubted worldwide airmail rarity, expertized by S. Wolf (Image)