Gudivok P. M., Oros V. M., and Roiter A. V. 1992. “Representations of Finite P-Groups over the Ring of Formal Power-Mode Series With Integral P-Addic Coefficients”. Ukrains’kyi Matematychnyi Zhurnal 44 (6), 753-65. https://umj.imath.kiev.ua/index.php/umj/article/view/8006.