1. Department of Mathematics, College of Education for Pure Sciences, University of Basrah, Basrah 61001, Iraq
2. Department of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia
3. Department of Mathematics and Computer Science, University of Oradea, 1 Universitatii Street, 410087 Oradea, Romania