BEREZANSKY, Yu. M.; GORBACHUK, V. I.; GORBACHUK, M. L. Functional Analysis in the Institute of Mathematics of the National Academy of Sciences of Ukraine. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 57, n. 5, p. 582–600, 2005. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3625. Acesso em: 5 dec. 2025.