1. Department of Mathematics, The Technion — Israel Institute of Technology, Haifa, Israel
2. Department of Mathematics and Informatics, Thai Nguyen University of Sciences, Thai Nguyen, Vietnam
3. Faculty of Science and Technology, Department of Mathematics and Computer Science, Rajamangala University of Technology Thanyaburi (RMUTT), Pathumthani, Thailand
4. School of Science, University of Phayao, Phayao, Thailand