Authors
Mohamed Rossafi
Department of Mathematics, University of Ibn Tofail Kenitra, Morocco
Samir Kabbaj
Department of Mathematics, University of Ibn Tofail Kenitra, Morocco
© 2019 Mohamed Rossafi, Samir Kabbaj, published by Pedagogical University of Cracow
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.