@BOOK {MULONGOY:1992a, title = {Biological nitrogen fixation and sustainability of tropical agriculture}, editor = {Mulongoy, K. and Gueye, M. * and Spencer, D. }, year = {1992}, publisher = {John Wiley & Sons; Sayce Publishing; International Institute of Tropical Agriculture(IITA); AABNF}, address = {Ibadan, Nigeria}, isbn = {0-471-98560-3}, note = {502p.}, }