Piffer, Silvano, et al. “Rubella Immunity Status and the Active Offer of MMR MMRV Vaccination During Pregnancy”. Annali dell’Istituto Superiore Di Sanità, vol. 57, no. 1, Mar. 2021, pp. 26-32, https://annali.iss.it/index.php/anna/article/view/1050.