@book{17932,
	author = {Ayanaba, A. and International Institute of Tropical Agriculture. },
	title = {Biological nitrogen fixation in farming systems of the tropics /},
	publisher = {Wiley,},
	year = {1977.},
	address = {Chichester, NY :},
	note = {"Based on papers presented at a Symposium held at the International Institute of Tropical Agriculture, Ibadan, Nigeria, in October 1975.}
}