1. Department of Mathematics, Faculty of Sciences; Al Imam Mohammad Ibn Saud Islamic University (IMSIU); PB 90950 Riyadh 11623 Saudi Arabia
2. Laboratoire “Théorie du Point Fixe et Applications” ENS; BP 92 Kouba Algiers 16006 Algeria
3. Département de Maths-Informatique; Hamma Lakhdar University; El-Oued 39000