1. School of Economics, Guangdong University of Finance and Economics, Guangzhou, P. R. China
2. Department of Mathematics, Sun Yat-sen University, Guangzhou, P. R. China
3. School of Statistics and Mathematics, Guangdong University of Finance and Economics, Big data and Educational Statistics Application Laboratory, Guangzhou, P. R. China
4. School of Statistics and Mathematics, Guangdong University of Finance and Economics, Guangzhou, P. R. China
5. Department of Mathematics and Statistics, University of Swat, Charbagh, kpk, Pakistan
6. Department of Mathematics, Faculty of Science, King Mongkut’s University of Technology, (KMUTT), Bangkok, Thailand