Yezhov II, Kadankov VF, Kadankova TV. Two-boundary problems for a random walk. Ukr. Mat. Zhurn. [Internet]. 2007 Nov. 25 [cited 2025 Dec. 6];59(11):1485–1509. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3406