ROMANYUK, A. S. Best trigonometric and bilinear approximations for the Besov classes of functions of many variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 47, n. 8, p. 1097–1111, 1995. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5506. Acesso em: 5 dec. 2025.