Markin, M. V. “On Scalar-Type Spectral Operators and Carleman Ultradifferentiable C0-Semigroups”. Ukrains’kyi Matematychnyi Zhurnal 60, no. 9 (September 25, 2008): 1215 – 1233. Accessed December 6, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/3238.