LYTVYNOV, E. V. On the existence of a cyclic vector for some families of operators. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 10, p. 1362–1370, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5941. Acesso em: 5 dec. 2025.