ROMANYUK, A. S. Entropy numbers and the widths of the classes $B_{p,θ}^r$ of periodic functionsof many variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 10, p. 1403–1417, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1928. Acesso em: 6 dec. 2025.