Gudivok, P. M., and E. Y. Pogorilyak. 2002. “Matrix Representations of Finite $p$-Groups over Commutative Local Rings of Characteristic $p^s$”. Ukrains’kyi Matematychnyi Zhurnal 54 (6), 764-70. https://umj.imath.kiev.ua/index.php/umj/article/view/4114.