First Author:   Armand Mboutchouang kountchou University of Dschang armand.mboutchouang@univ-dschang.org   Dschang, 237, Cameroon   675133309(Phone) 675133309(Fax) https://sites.google.com/view/armand-mboutchouang-kountchou Second Author: Steve kevin Ngangni University of Douala kevinsteve813@gmail.com   Douala, 237, Cameroon   678935567(Phone)   Third Author: Linda Zanfack tiague University of Dschang zanfacktiaguel@yahoo.com   Dschang, 237, Cameroon   696536467(Phone)