1. Department of Mathematics, Faculty of Science, King Khalid University, P. O. Box 25145, Abha 61466, Saudi Arabia;
2. Department of Mathematics, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
3. Department of Mathematics, College of Science and Arts at Khulis, University of Jeddah, Jeddah 21921, Saudi Arabia;
4. Department of Mathematics, Faculty of Science, Al-Azhar University (Assiut Branch), Assiut, Egypt
5. Department of Mathematics, Faculty of Science and Arts, King Khalid University, Mhayal Asier 61913, Saudi Arabia;
6. Department of Mathematics, Faculty of Science, Beni-Suef University, Beni Suef 62521, Egypt