Ban, Đoàn Văn, Doãn Ngọc Liên, and Hoàng Quang. “Some Problems on Object-Oriented Software System Modeling”. Journal of Computer Science and Cybernetics 18, no. 4 (July 27, 2012): 375–383. Accessed April 27, 2024. https://vjs.ac.vn/index.php/jcc/article/view/1576.