LimanF. N., and LukashovaT. D. “On the Norm of Decomposable Subgroups in Nonperiodic Groups”. Ukrains’kyi Matematychnyi Zhurnal 67, no. 12 (December 25, 2015): 1679-1689. Accessed October 6, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2100.