Hanagal, D. D. ., and R. A. . Kanade. “OPTIMAL REPLACEMENT POLICIES BASED ON NUMBER OF DOWN TIMES FOR COLD STANDBY SYSTEM WHEN THE LIFETIME AND THE REPAIR TIME ARE DEPENDENT”. Journal of Reliability and Statistical Studies, vol. 4, no. 1, June 2011, pp. 41-52, https://journals.riverpublishers.com/index.php/JRSS/article/view/21993.