Litvinov, A. N., and I. I. Repin. 1971. “On Closeness of Distributions of Two Markovian Sums of Random Variables Without a Condition of Limit Neglections ”. Ukrains’kyi Matematychnyi Zhurnal 23 (2): 248-53. https://umj.imath.kiev.ua/index.php/umj/article/view/8509.