Korolev, A. V. “On the Ergodic Theorem in the Kozlov–Treshchev Form for an Operator Semigroup”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 62, no. 5, May 2010, pp. 702–707, https://umj.imath.kiev.ua/index.php/umj/article/view/2901.