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2. Cancer of the liver in the Negro in Africa and America;Kennaway;Cancer Res.,1944
3. Rarity of testis cancer in Negroes;Tulinius;Lancet,1975
4. Regional Influences in Cancer;Cruickshank;Br. J. Cancer,1947
5. The Role of geographical pathology in environmental carcinogenesis;Higginson,1972