STASYUK, S. A. Best M-term orthogonal trigonometric approximations of the classes B Ωp,θ of periodic functions of many variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 5, p. 647 – 656, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3183. Acesso em: 5 dec. 2025.