Registered cover with 'Departamento Nacional de Higiene Instituto Bacteriologico' imprint on front franked with 1923 1c buff and pair 12c blue 'San Martin' issue with 'M.I.' Ministry of Interior official overprints (SG OD31D & OD34D) tied by BUENOS AIRES cds's and by official signature handstamp in purple with printed registration label alongside. Addressed to USA with various transit & arrival marks on reverse.