Kazarin , L. S. “Product of a Group With Cyclic Force P-Subgroup and a Group With a Nontrivial Centre”. Ukrains’kyi Matematychnyi Zhurnal 44, no. 6 (July 7, 1992): 773–779. Accessed April 14, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/8008.