Bobrowski, A. “The Widder-Arendt Theorem on Inverting of the Laplace Transform, and Its Relationships With the Theory of Semigroups of Operators”. Methods of Functional Analysis and Topology 3, no. 4 (December 25, 1997): 1–39. Accessed December 19, 2025. https://zen.imath.kiev.ua/index.php/mfat/article/view/46.