TOVKACH, R. V. Approximation of some classes of periodic functions of many variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 8, p. 1149–1152, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2945. Acesso em: 5 dec. 2025.