ANASTASSIOU, G. A. Approximation by discrete singular operators. CUBO, A Mathematical Journal, [S. l.], v. 15, n. 1, p. 97–112, 2013. DOI: 10.4067/S0719-06462013000100006. Disponível em: https://cubo.ufro.cl/ojs/index.php/cubo/article/view/1321. Acesso em: 13 may. 2024.