Lyman, F. N., and T. D. Lukashova. “On the Norm of Decomposable Subgroups in Locally Finite Groups”. Ukrains’kyi Matematychnyi Zhurnal, vol. 67, no. 4, Apr. 2015, pp. 480-8, https://umj.imath.kiev.ua/index.php/umj/article/view/1998.