1. Department of Mathematics, Faculty of Arts and Science, Amman Arab University, Amman 11953, Jordan
2. Department of Mathematics, Faculty of Science, Yarmouk University, Irbid 22163, Jordan
3. Department of Mathematics, Faculty of Science, The Hashemite University, P.O. Box 330127, Zarqa 13133, Jordan
4. Department of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Malaysia