A. Y. . Olshansky, “Nesting of periodical groups into simple periodica groups”, Ukr. Mat. Zhurn., vol. 44, no. 6, pp. 845–847, Jul. 1992, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/8021