ZuzukL. I. “Construction of Nonnilpotent Biprimary Dispersible Groups With Metacyclic Subgroups of Nonprimary Index”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 49, no. 6, June 1997, pp. 849–851, https://umj.imath.kiev.ua/index.php/umj/article/view/5071.