1. School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China
2. School of Mathematics and Statistics, Wuhan University, Wuhan, People’s Republic of China
3. Thai Nguyen University of Education, Department of Mathematics, Luong Ngoc Quyen street, Thai Nguyen city, Thai Nguyen, Viet Nam + Thang Long Institute of Mathematics and Applied Sciences, Thang Long University, Nghiem Xuan Yem, Hoang Mai, Hanoi, Viet Nam