First Author:   Alain Biakolo Onana University of Yaounde II biaonana@gmail.com   biaonana@gmail.com YAOUNDE, CAMEROUN   697351651(Phone) 697351651(Fax) Second Author: Xaverie-Euphemie Okah Atenga University of Yaounde II okataxe@yahoo.fr         Third Author: Mohaman Gabdo Tamboutou University of Yaounde II gabdotamboutou@gmail.com         Fourth Author: Bmermoz Homere III Nsoga Nsoga University of Yaounde II ogamermoz@yahoo.fr         http://