Soemadi, K., B. P. Iskandar, and H. Taroepratjeka. “Optimal Overhaul-Replacement Policies for Repairable Machine Sold With Warranty”. Journal of Engineering and Technological Sciences, vol. 46, no. 4, Dec. 2014, pp. 465-83, doi:10.5614/j.eng.technol.sci.2014.46.4.9.