STASYUK, S. A. Trigonometric Widths of the Classes $B_{p,θ}^{Ω}$ of Periodic Functions of Many Variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 54, n. 5, p. 700–705, 2002. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4109. Acesso em: 6 dec. 2025.