BOGDANSKII, Yu. V. Infinite-dimensional version of the Friedrichs inequality. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 70, n. 11, p. 1476–1483, 2018. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1651. Acesso em: 14 apr. 2025.