I  Grotto, Balicer, RD , Smetana, Z , Davidovitch, N , Bar-Zeev, Y , Mendelson, E , Zarka, S , and Huerta, M . 2008. ?Immunity To Varicella Zoster Virus Among Young Adults: A Decline Prior To Widespread Uptake Of Varicella Vaccines?. Infection, 36, Pp. 130?134.