Y. M. Arlinskii, “Operator-norm approximations of holomorphic one-parameter semigroups of contractions in Hilbert spaces”, MFAT, vol. 18, no. 2, pp. 101–110, Jun. 2012, Accessed: Dec. 16, 2025. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/508