1. Research Center for Mathematics and Mathematics Education, Beijing Normal University at Zhuhai, Zhuhai, People's Republic of China
2. Laboratory of Mathematics and Complex Systems (Ministry of Education), School of Mathematical Sciences, Beijing Normal University, Beijing, People's Republic of China
3. Department of Mathematics, Faculty of Science and Technology, University of Macau, Macao, People's Republic of China
4. Department of Mathematics, Zhejiang Normal University, Jinhua, People's Republic of China
5. Department of Mathematics, Wuyi University, Jiangmen, People's Republic of China