STEPANETS, O. I. Approximation of $\bar {\psi} - integrals$−integrals of periodic functions by Fourier sums (small smoothness). Iof periodic functions by Fourier sums (small smoothness). I. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 2, p. 274–291, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4961. Acesso em: 5 dec. 2025.