1. University of Maroua,Department of Computer Science,Maroua,Cameroon
2. University of Ngaoundéré,Department of Computer Engineering,Ngaoundéré,Cameroon
3. University of Versailles St-Quentin-en-Yvelines,DAVID Lab,Versailles Cedex,France,78035
4. Texas A&M University-Central,Department of Mathematics,Texas Killeen,USA
5. University Bourgogne Franche-Comté,LIB EA7534,Dijon,France,21078