YANCHENKO, S. Ya. Best approximation of the functions from anisotropic Nikol’skii – Besov classes defined in $R^d$. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 70, n. 4, p. 574–582, 2018. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1577. Acesso em: 5 dec. 2025.