Cường, Bùi Công, Hoàng Việt long, and Phạm Hồng Phong. “On the Approximation of Continous Function by Spline Function Hireachical Fuzzy Systems”. Journal of Computer Science and Cybernetics 25, no. 2 (April 27, 2012): 99–108. Accessed November 5, 2025. https://jcc.vast.vn/jcc/article/view/563.