@ARTICLE {MANYONG:1997, title = {Spatial patterns of biological constraints to cassava and yam production in West and Central Africa: Implications for technology development and transfer}, author = {Manyong, V. and Oyewole, B. }, journal = {African Journal of Root and Tuber Crops}, year = {1997}, volume = {3}, pages = {15--21}, note = {RTB; Root and Tuber.; IITA Technologies}, }