K. E. Stewien and J. P. G. de Lacerda, “ Application of the neutralization index comparison technique to the intratypic serodifferentiation of type 1 and 3 poliovirus strains, using Hep-2 cell cultures ”, Rev. saúde pública, vol. 9, no. 2, pp. 221–228, Jun. 1975, doi: 10.1590/S0034-89101975000200012.