1. LAMDA-RO Laboratory Department of Mathematics University of Blida 1 Po. Box 270 Route de Soumaa, Blida, Algeria mohamed77dilmi@gmail.com
2. Applied Mathematics Laboratory Department of Mathematics Setif University, 19000, Algeria aissa.benseghir@univ-setif.dz
3. Applied Mathematics Laboratory Department of Mathematics Setif University, 19000, Algeria mourad.dilmi@univ-setif.dz
4. Applied Mathematics Laboratory Department of Mathematics Setif University, 19000, Algeria hamid.benseridi@univ-setif.dz