1. Laboratory of Analysis and Control of P.D.E, University of Sidi Bel Abbes, Algeria. / University Center of Naama, Department of Mathematics and Computer Sciences, 45100 Naama, Algeria.
2. University Center of Naama, Department of Mathematics and Computer Sciences, 45100 Naama, Algeria.
3. Djillali Lyabes University of SBA, Department of Probabilities and Statistics, 22000 Sidi Bel Abbes, Algeria.