Zabavskii, B. V. “A Noncommutattve Analog of the Cohen Theorem”. Ukrains’kyi Matematychnyi Zhurnal 48, no. 5 (May 25, 1996): 707–710. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5304.