1. Department of Mathematics, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok, Thailand
2. Center of Excellence in Theoretical and Computational Science (TaCS-CoE), King Mongkut's University of Technology Thonburi, Bangkok, Thailand
3. Department of Mathematics, Guru Ghasidas Vishwavidyalaya, Bilaspur, India
4. Department of Mathematics, University of Jaen, Jaén, Spain