Polovitskii, Y. D., N. S. Chernikov, and V. L. Chechulin. “Groups With Incidence Condition for Noncyclic Subgroups”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 48, no. 4, Apr. 1996, pp. 533-9, https://umj.imath.kiev.ua/index.php/umj/article/view/5316.