Ocurrence of non-toxigenic vibrio cholerae 0: 1 in wastewaters from sao paulo, brazil - Martins, Maria Therezinha; Pessoa, G V A; Sanchez, P S; Sato, M I Z; Coimbrao, C A; Monteiro, C K; Marques, E (International Symposium on Health-Related Water Microbiology, 1990)