Furuta, J.A. (1982) “ Quantitative determination of diphtheria antibodies in guinea pigs: I - persistency of diphtheria antitoxin levels in sera of animals inoculated with diphtheria toxoid ”, Revista de Saúde Pública, 16(2), pp. 97–106. doi:10.1590/S0034-89101982000200005.