8Katz MH, Hsu L, Wong E, et al. Seroprevalence of and risk factors for hepatitis A infection among young homosexual and bisexual men. J Infect Dis, 1997, 175(5): 1225-1229.
9Stewart T, Crofts N. An outbreak of hepatitis A among homo-sexual men in Melbourne. Med J Aust, 1993, 158(8): 519-521.
10Szmuness W, Much I, Prince AM, et al. On the role of sexual behavior in the spread of hepatitis B infection. Ann Intern Med, 1975, 83(4): 489-495.