D. I. Zaitsev, “Groups satisfying a weak minimum condition for non-Abelian subgroups”, Ukr. Mat. Zhurn., vol. 23, no. 5, pp. 661–665, Sep. 1971, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/8337