Wróbel, I., A. M. Gomilko, and J. Zemanek. “On a Criterion for the Uniform Boundedness of a <i>C</i><sub>0</Sub&gt;-Semigroup of Operators in a Hilbert Space”. Ukrains’kyi Matematychnyi Zhurnal 59, no. 6 (June 25, 2007): 853-858. Accessed March 28, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3350.