THI, V. Đức. Some results about relations in the relational datamodel. Journal of Computer Science and Cybernetics, [S. l.], v. 17, n. 1, p. 31–34, 2012. DOI: 10.15625/1813-9663/17/1/2426. Disponível em: https://vjs.ac.vn/index.php/jcc/article/view/2426. Acesso em: 27 apr. 2024.