Furuta, J.A. et al. 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 (Apr. 1982), 97–106. DOI:https://doi.org/10.1590/S0034-89101982000200005.