APA
Norman D. W., Simmons E. B. & Hayes H. M. (1982). Farming systems in the Nigerian savanna. Boulder: Westview Press.
Chicago
Norman D W, Simmons Emmy Bartz and Hayes Henry Merlin. 1982. Farming systems in the Nigerian savanna. Boulder: Westview Press.
Harvard
Norman D. W., Simmons E. B. and Hayes H. M. (1982). Farming systems in the Nigerian savanna. Boulder: Westview Press.
MLA
Norman D W, Simmons Emmy Bartz and Hayes Henry Merlin. Farming systems in the Nigerian savanna. Boulder: Westview Press. 1982.