ZADEREI, P. V. Approximation of $(\bar \psi ,\bar \beta )$ -differentiable periodic functions of many variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 3, p. 367–377, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5818. Acesso em: 5 dec. 2025.