@INBOOK {SHANNON:1991, title = {Issues in on-farm experimentation at Gandajika, Zaire}, author = {Shannon, D. A. and Kubeng, M. and Mpoy, M. C. }, year = {1991}, type = {On-farm research in theory and practice, edited by H.J.W. Mutsaers and P. Walker}, pages = {188--197}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, }