@book{32796,
	author = {Norman, David W. and Newman, Mark D.},
	title = {Farm and village production systems in the semi-arid tropics of west Africa ; an interpretative review of research},
	publisher = {International Crops Institute for the Semi-Arid Tropics,},
	year = {1981},
	series = {Research bulletin},
	address = {Patancheru :}
}