Grados, O. B. (April 1975). "[The laboratory in programs for enteric infection control]". Boletin de la Oficina Sanitaria Panamericana. Pan American Sanitary Bureau. 78 (4): 318–322. ISSN0030-0632. PMID123456.
Grados, O. B. (April 1975). "[The laboratory in programs for enteric infection control]". Boletin de la Oficina Sanitaria Panamericana. Pan American Sanitary Bureau. 78 (4): 318–322. ISSN0030-0632. PMID123456.