SERDYUK, A. S.; STEPANETS, O. I. Approximation by fourier sums and best approximations on classes of analytic functions. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 3, p. 375–395, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4428. Acesso em: 6 dec. 2025.