MELNIK , Yu. I. Inverse theorems of approximation of regular (in convex polygons) functions by exponential polynomials in the integral metric. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 40, n. 6, p. 751–757, 1988. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/9285. Acesso em: 5 dec. 2025.