THI, V. Đức. Some computational problems related to normal forms. Journal of Computer Science and Cybernetics, [S. l.], v. 13, n. 1, p. 53–65, 2016. DOI: 10.15625/1813-9663/13/1/7983. Disponível em: https://vjs.ac.vn/index.php/jcc/article/view/7983. Acesso em: 20 apr. 2024.