Kozachenko, M. Yu. “Necessary and Sufficient Condition of Isomorphism for Multiplicative and Additive Systems Without Continuity Condition With the Accuracy up to Grinding Divisions ”. Ukrains’kyi Matematychnyi Zhurnal 40, no. 5 (August 29, 1988): 576–583. Accessed April 7, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/8805.