BUSHEV, D. M. Isometry of functional spaces with different number of variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 8, p. 1027–1045, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4852. Acesso em: 5 dec. 2025.