First Author:   Manuela CHETUE Komguep University of Dschang, Cameroon manoukomguep@yahoo.fr   manoukomguep@yahoo.fr Dschang, CAMEROON   +237691221653(Phone) +237691221653(Fax) Second Author: Luc NDEFFO Nembot University of Dschang, Cameroon ndefluc@yahoo.fr   Dschang   +237 696968298(Phone)