STASYUK, S. A. Best approximation of periodic functions of several variables from the classes $MB^{\omega}_{p,\theta}$. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 64, n. 1, p. 140–144, 2012. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2561. Acesso em: 11 apr. 2025.