Torba, S.M. and Grushka, Y.I. (2007) “Direct theorems in the theory of approximation of Banach space vectors by exponential type entire vectors”, Methods of Functional Analysis and Topology, 13(3), pp. 267–278. Available at: https://zen.imath.kiev.ua/index.php/mfat/article/view/354 (Accessed: 16 December 2025).