@INBOOK {NWEKE:1988e, title = {Collecting and interpreting relevant data required to link research results from varying environments: an economist's perspective}, author = {Nweke, F. }, year = {1988}, type = {Cassava-based cropping systems research 1}, pages = {37--45}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, }