DERECH, V. D. Congruences of a Permutable Inverse Semigroup of Finite Rank. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 57, n. 4, p. 469–473, 2005. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3613. Acesso em: 27 apr. 2025.