@BOOK {CLAASSEN:1992, title = {Produits agrochimiques en station de recherche: Guide de recherche de l'Iita, No. 17}, author = {Claassen, S. L. }, series = {Guide de recherche de l'Iita, No. 17}, year = {1992}, month = {February}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, note = {12p.}, }