ZADEREI, P. V.; SMAL, ' B. M. Estimates for the best approximation and integral modulus of continuity of a function in terms of its Fourier coefficients. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 4, p. 496–503, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4919. Acesso em: 5 dec. 2025.