1. Laboratoire d'Analyse Non Linéaire et Mathématiques Appliquées Université de Tlemcen Tlemcen Algeria
2. Department of Mathematics, Faculty of Exact Sciences and Computer Science Hassiba Benbouali University Chlef Algeria
3. Department of Mathematics Wilfrid Laurier University Waterloo Ontario Canada
4. Department of Mathematics and Informatics University Ain Temouchent Belhadj Bouchaib BP 284 RP, 46000 Algeria