Nghia, Nguyen. “APPROXIMATION SOLUTIONS OF A SYSTEM OF FUNCTIONAL EQUATIONS IN A TWO-DIMENSIONAL DOMAIN”. VNUHCM Journal of Science and Technology Development 5, no. 1&2 (February 28, 2002): 56-65. Accessed September 27, 2025. http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/3402.