1. Department of Mathematics, Teacher College, Cantho University, Cantho, Vietnam
2. Department of Mathematics, Vo Truong Toan University, Haugiang, Vietnam
3. Division of Computational Mathematics and Engineering, Institute for Computational Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam
4. Faculty of Mathematics and Statistics, Ton Duc Thang University, Ho Chi Minh City, Vietnam