ROMANYUK, A. S. On estimates of approximation characteristics of the Besov classes of periodic functions of many variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 9, p. 1250–1261, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5124. Acesso em: 5 dec. 2025.