Epidemiological studies on the HBV infection among the children at school age in S village in Gifu prefecture: Observation of anti-HBs positive for 6 years - MUTO, Yasutoshi; KAMETANI, Masaaki; TOKIMITSU, Naoki; GOI, Reiji; OKANO, Yasumasa; TSUDA, Fumio; TAKAKUWA, Kaoru; IWAI, Shoko; SUGIYAMA, Masato; TANAHASHI, Shinobu (Kanzo, 1984)