@book{135866,
	author = {Ayanaba, A. and Dart, J.p.},
	title = {Biological nitrogen fixation in farming systems of the tropics},
	publisher = {John Wiley & Sons},
	year = {1977},
	address = {New York},
	note = {Basado en trabajos presentados en el Symposium   del Institute International of Tropical Agriculture, Ibadan, Nigeria , oct 1975}
}