Affiliation: | 1. Department of Mathematics, University of Science, Vietnam National University, 227 Nguyen Van Cu Street, District 5, Ho Chi Minh City, Viet Nam;2. Faculty of Basic Science, Ho Chi Minh City University of Transport, 2 Vo Oanh Street, Binh Thanh District, Ho Chi Minh City, Viet Nam;3. Department of Fundamental Studies, Ho Chi Minh City Open University, 97 Vo Van Tan Street, District 3, Ho Chi Minh City, Viet Nam |