@BOOK {COUPER:1993b, title = {Le non-labour dans les tropiques humides et subhumides d'Afrique: Guide de recherche de l'Iita, No. 3}, author = {Couper, D. C. }, series = {Guide de recherche de l'Iita, No. 3}, year = {1993}, month = {April}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, note = {25p.}, }