Bratiichuk, M. S., A. A. Chechelnitsky, and I. Ya. Usar. “M/M/1//Retrial/Queueing/Model/With/Variable/Service/Rate”. Ukrains’kyi Matematychnyi Zhurnal 72, no. 3 (March 28, 2020): 355–365. Accessed April 26, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/813.