TORBA, S. M.; GRUSHKA, Ya. I. Direct theorems in the theory of approximation of Banach space vectors by exponential type entire vectors. Methods of Functional Analysis and Topology, [S. l.], v. 13, n. 3, p. 267–278, 2007. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/354. Acesso em: 16 dec. 2025.