Liman, F. N., and T. D. Lukashova. “On the Norm of Decomposable Subgroups in Nonperiodic Groups”. Ukrains’kyi Matematychnyi Zhurnal 67, no. 12 (December 25, 2015): 1679–1689. Accessed February 1, 2026. https://umj.imath.kiev.ua/index.php/umj/article/view/2100.