1. Department of Mathematics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand
2. Department of Mathematical Sciences, Fatima Jinnah Women University, Islamabad, Pakistan
3. Department of Mathematics, Azarbaijan Shahid Madani University, Tabriz, Iran
4. Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan