Chernikov , S. N., and S. S. Levishchenko. “Constructive Description of Finite Nondispersed Groups Where All Subgroups of the Nonprimary Index Are Abelian ”. Ukrains’kyi Matematychnyi Zhurnal 44, no. 6 (July 7, 1992): 818–822. Accessed December 6, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/8015.