Kuzenny , N. F., and N. N. Semko. 1988. “Structure of Periodic Metabelian Metahamiitonian Groups With an Elementary Commutant of Rank Two”. Ukrains’kyi Matematychnyi Zhurnal 40 (6): 743-50. https://umj.imath.kiev.ua/index.php/umj/article/view/9284.