Xiaolan, Y., and O. L. Shemetkova. “Finite Groups With System of <em class="a-Plus-plus">SE</Em&gt;-Supplemented Subgroups”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 65, no. 9, Sept. 2013, pp. 1227–1235, https://umj.imath.kiev.ua/index.php/umj/article/view/2503.