1. Department of Mathematics and Statistics, Hazara University, Mansehra, Pakistan
2. Department of Mathematics, University of Sargodha P.O. Box 40100, Sargodha, Pakistan
3. Department of Mathematics, Faculty of Technical and Natural Sciences, University "Ismail Qemali", 9400 Vlora, Albania
4. Department of Mathematics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand