WRÓBEL, I.; GOMILKO, A. M.; ZEMANEK, J. On a criterion for the uniform boundedness of a C0-semigroup of operators in a Hilbert space. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 59, n. 6, p. 853–858, 2007. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3350. Acesso em: 6 dec. 2025.