Samoilenko, I. V. “Asymptotic Expansion of a Semi-Markov Random Evolution”. Ukrains’kyi Matematychnyi Zhurnal 58, no. 9 (September 25, 2006): 1234–1248. Accessed May 2, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3524.