Zaitsev, D. I. “Groups Satisfying a Weak Minimum Condition for Non-Abelian Subgroups”. Ukrains’kyi Matematychnyi Zhurnal 23, no. 5 (September 3, 1971): 661–665. Accessed December 6, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/8337.