$\cal P$-Congruence-Free Epigroups. Communications in Mathematical Research, [S. l.], v. 33, n. 2, p. 97–109, 2019. DOI: 10.13447/j.1674-5647.2017.02.01. Disponível em: https://global-sci.com/index.php/cmr/article/view/8917. Acesso em: 6 dec. 2025.