SERDYUK, A. S.; STEPANYUK, T. A. Order Estimates for the Best Orthogonal Trigonometric Approximations of the Classes of Convolutions of Periodic Functions of Low Smoothness. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 67, n. 7, p. 916–936, 2015. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2033. Acesso em: 6 dec. 2025.