Polovitskii, Ya. D., N. S. Chernikov, and V. L. Chechulin. “Groups With Incidence Condition for Noncyclic Subgroups”. Ukrains’kyi Matematychnyi Zhurnal 48, no. 4 (April 25, 1996): 533-539. Accessed May 17, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5316.