1. Billinghurst, J. R. and J. M. Welchmann: Idiopathic ulcerative colitis in the African: A report of 4 cases. Brit. M. J.1: 211, 1966.
2. Cattell, R. B., D. H. MacKenzie and B. P. Colcock: Cancer of the colon and rectum. S. Clin. North America.35: 823, 1955.
3. Clemmesen, J. and A. Nielsen: The incidence of malignant diseases in Denmark 1943 to 1947. Acta Unio internat. contra cancrum.8: 140, 1952.
4. Davies, J. N. P.: The results achieved by the Kampala cancer survey. Acta Unio internat. contra cancrum.13: 891, 1957.
5. Davies, J. N. P., J. Knowelden and B. A. Wilson: Incidence rates of cancer in Kyadondo County, Uganda, 1954–1960. J. Nat. Cancer Inst.35: 789, 1965.