Thi, Vũ Đức, and Nguyễn Hoàng Sơn. “Desribing Minimal Keys by Dense Families of Database Relations”. Journal of Computer Science and Cybernetics 21, no. 2 (July 24, 2012): 130–136. Accessed May 3, 2024. https://vjs.ac.vn/index.php/jcc/article/view/1444.