ROMANYUK, A. S. On the Problem of Linear Widths of the Classes $B_{p,θ}^r$ of Periodic Functions of Many Variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 66, n. 7, p. 970–982, 2014. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2192. Acesso em: 5 dec. 2025.