Li, Shirong, and Jianjun Liu. “CLT-Groups With Hall S-Quasinormally Embedded Subgroups”. Ukrains’kyi Matematychnyi Zhurnal, vol. 66, no. 8, Aug. 2014, pp. 1146–1152, https://umj.imath.kiev.ua/index.php/umj/article/view/2205.