SERDYUK, A. S. Estimates of the Kolmogorov widths for classes of infinitely differentiable periodic functions. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 12, p. 1700–1706, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5176. Acesso em: 5 dec. 2025.