1. Laboratory LAMA, Faculty of Sciences Dhar El Mahraz, Department of Mathematics, Sidi Mohamed Ben Abdellah University, Atlas Fez, Morocco.
2. Laboratory LSI, Poly-Disciplinary Faculty of Taza, Department MPI, Sidi Mohamed Ben Abdellah University, Taza Gare, Morocco.
3. Faculté des Sciences Juridiques, Economiques et Sociales, Université Hassan 1, Settat, Morocco.