TƯỜNG, Nguyễn Bá. The key and normal forms in relation scheme. <b>Journal of Computer Science and Cybernetics</b>, <i>[S. l.]</i>, v. 16, n. 4, p. 30–33, 2013. DOI: 10.15625/1813-9663/16/4/2920. Disponível em: https://vjs.ac.vn/jcc/article/view/2920. Acesso em: 5 dec. 2025.