1. International Center for Complex Systems, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaounde, Cameroon
2. Complex Systems, Faculty of Science, University of Maroua, P.O. Box 814, Maroua, Cameroon
3. Centre Africain d’Excellence en Technologies de l’Information et de la Communication, B.P. 812 Yaoundé, Cameroon