@BOOK {KANG:1997a, title = {Les engrais; definitions et calculs: Guide de recherche de l'Iita, No. 24}, author = {Kang, B. T. }, series = {Guide de recherche de l'Iita, No. 24}, year = {1997}, month = {January}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, note = {28p.}, }