CHRONOWSKI, A. Congruences on ternary semigroups. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 56, n. 4, p. 544–559, 2004. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3775. Acesso em: 6 dec. 2025.