Malan’ina, G. A., and N. S. Chernikov. “One Condition of Complementability in Groups”. Ukrains’kyi Matematychnyi Zhurnal 48, no. 10 (October 25, 1996): 1417-1425. Accessed May 18, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5227.