Bakuli, Kuntal, and Manisha Pal. “A Two-Server Bulk Service Queuing Model With a Permanent Server and a Temporary Server on Hold”. Thailand Statistician 20, no. 3 (June 29, 2022): 636–654. Accessed May 6, 2024. https://ph02.tci-thaijo.org/index.php/thaistat/article/view/246994.