ROMANYUK, A. S. Estimates for Approximation Characteristics of the Besov Classes $B_ r^{p,θ}$ of Periodic Functions of Many Variables in the Space $L_q. I$. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 53, n. 9, p. 1224–1231, 2001. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4341. Acesso em: 6 dec. 2025.