1. Utsunomiya T, Suzuki K, Shinohara H, et al: Epidemiology of ulcerative colitis. Clinical gastroenterology 1987;187–198 (in Jpn)
2. Kimura A, Sasagawa T: Incidence of Crohn’s disease in Japan. In: Shiratori T, ed.: Inflammatory bowel disease. University of Tokyo Press, Tokyo. 1984;191–200
3. World Health Organization (WHO): International classification of disease, 1975 rev vol 1. WHO, Geneva. 1977
4. Statistics and Information Department, Minister’s Secretariat, Ministry of Health and Welfare: Vital Statistics Japan. Tokyo. 1969–1985
5. Epidemiology of Intractable Disease Research Committee: Mortality statistics of intractable diseases in Japan, 1969–1978. Nagoya. 1984;31–296