Gupta, R. “Cost Optimization of Queueing System With Working Vacation, Setup, Feedback, Reneging, and Retention of Reneged Customers”. Journal of Scientific Research 14, no. 1 (January 1, 2022): 257–268. Accessed August 31, 2024. https://banglajol.info/index.php/JSR/article/view/55075.