Souza, Vanda A.U.F., et al. “ Prevalence of Rubella Antibodies in a Non-Immunized Urban Population, São Paulo, Brazil ”. Revista Do Instituto De Medicina Tropical De São Paulo, vol. 36, no. 4, Aug. 1994, pp. 373-6, https://www.revistas.usp.br/rimtsp/article/view/29180.