Mel'nik, T.I. (2002) “Varieties of Groups with Invariant Centralizers of Subgroups”, Ukrains’kyi Matematychnyi Zhurnal, 54(4), pp. 483–491. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4086 (Accessed: 10 April 2025).