1. Department of Mathematics, Faculty of Science, King Saud University, Riyadh, Saudi Arabia
2. Department of Mathematics, Faculty of Science, Imam Muhammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
3. Department of Mathematics, College of Science, University of Ha’il, Ha’il 2440, Saudi Arabia
4. Department of Mathematics and Statistics, Fourah Bay College, University of Sierra Leone, Sierra Leone