1. Department of Mathematics, Faculty of Science, Maejo University, Chiang Mai 52290, Thailand
2. Department of Mathematics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand
3. Department of Mathematics, Thiruvalluvar University, Vellore 632115, Tamilnadu, India
4. Rail System Institute of Rajamangala University of Technology Isan, Nakhon Ratchasima 30000, Thailand