Plichko A. M. “Automatic Continuity, Bases and Radicals in the Metrized Algebras ”. Ukrains’kyi Matematychnyi Zhurnal 44, no. 8 (September 8, 1992): 1129-1132. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/8046.