International Institute of Tropical Agriculture(Resource and Crop Management Program, International Institute of Tropical Agriculture, Ibadan, NG, 1988)
Malang Research Institute for Food Crops; Central Research Institute for Food Crops; Universitas Brawidjaya, Faculty of Agriculture(MARIF, Malang, ID, 1995)
International Council for Research in Agroforestry; Kenya Agricultural Research Institute; Hoekstra, D.A.; Wood, P.J.; Sang, F.A.(ICRAF, Nairobi, KE, 1988)