ROMANYUK, A. S. Approximation of Classes $B_{p,θ}^r$ by Linear Methods and Best Approximations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 54, n. 5, p. 670–680, 2002. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4106. Acesso em: 6 dec. 2025.