A. F. Al-Dababseh, “On τ-Closed Formations of n-Ary Group”, Ukr. Mat. Zhurn., vol. 53, no. 1, pp. 113–116, Jan. 2001, Accessed: Apr. 09, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/4226