@BOOK {COUPER:1993, title = {Utilisation des cartes dans la planification des fermes experimentales: Guide de recherche de l'Iita, No. 7}, author = {Couper, D. C. }, series = {Guide de recherche de l'Iita, No. 7}, year = {1993}, month = {May}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, note = {28p.}, }