Dao Chi Cuong. “DESIGN RESEARCH, MANUFACTURING DEVICE MEASURING THE OPACITY OF THE EXHAUST GAS OF THE INTERNAL COMBUSTION ENGINE”. UTEHY Journal of Science and Technology 34 (June 30, 2022): 31-37. Accessed December 4, 2022. https://tapchi.utehy.edu.vn/index.php/jst/article/view/537.