KashpurO. F., and KhlobystovV. V. “Analysis of the Accuracy of Interpolation of Entire Operators in a Hilbert Space in the Case of Perturbed Nodal Values”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 55, no. 7, July 2003, pp. 953-60, https://umj.imath.kiev.ua/index.php/umj/article/view/3970.