SERDYUK, A. S. Approximation of Periodic Functions of High Smoothness by Interpolation Trigonometric Polynomials in the Metric of $L_1$. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 7, p. 994–998, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4501. Acesso em: 6 dec. 2025.