Li, X. H., and Y. Xu. “$s$-Conditionally Permutable Subgroups and $p$-Nilpotency of Finite Groups”. Ukrains’kyi Matematychnyi Zhurnal 66, no. 6 (June 25, 2014): 858–864. Accessed April 26, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/2184.