Hoang Van Quy, and Bui Ngoc Tuyen. “AN ALGORITHM AND A SOFTWARE TOOL OF MODELING FREEFORM SURFACES FOR MECHANICAL ENGINEERING”. UTEHY Journal of Applied Science and Technology, Vol. 19, Oct. 2018, pp. 9-13, http://tapchi.utehy.edu.vn/index.php/jst/article/view/80.