ROMANYUK, A. S. Linear Widths of the Besov Classes of Periodic Functions of Many Variables. II. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 53, n. 6, p. 820–829, 2001. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4302. Acesso em: 27 apr. 2025.