Lopushansky, O.V., and S.V. Sharyn. “Functional Calculus for Generators of Analytic Semigroups of Operators”. Carpathian Mathematical Publications 4, no. 1 (June 28, 2012): 83–89. Accessed November 24, 2024. https://vps.pnu.edu.ua/index.php/cmp/article/view/2469.