Authors
Badr El Haji
Laboratory LAMA, Department of Mathematics, Faculty of Sciences Fez, University Sidi Mohamed Ben Abdellah, Fez, Morocco
Mostafa El Moumni
Department of Mathematics, Faculty of Sciences El Jadida, University Chouaib Doukkali, El Jadida, Morocco
Khaled Kouhaila
Laboratory LAMA, Department of Mathematics, Faculty of Sciences Fez, University Sidi Mohamed Ben Abdellah, Fez, Morocco