AL-DABABSEH, Avni Faez. On τ-Closed Formations of n-Ary Group. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 53, n. 1, p. 113–116, 2001. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4226. Acesso em: 5 dec. 2025.