Decline in the exposure to hepatitis A and B infections in children in Naples, Italy - D’Argenio, P; Esposito, D; Mele, A; Ortolani, G; Adamo, B; Rapicetta, M; Forte, P; Pisani, A; Soldo, L; Sarrecchia, B; Stroffolini, T; Pasquini, P (Public Health, 1989)