1. Department of Mathematical Sciences, Faculty of Science & Technology, Universiti Kebangsaan, Selangor, Malaysia
2. Department of Mathematics and Statistics, College of Science, Al-Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
3. Department of Mathematics, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
4. Department of Basic Sciences, Adham University College, Umm AL-Qura University, Makkah, Saudi Arabia
5. LAETA/INEGI, Faculty of Engineering, University of Porto, Porto, Portugal