Wimonmas Lengbamrung, and Adisak Pongpullponsak. 2009. “A Study of Optimal Burn-In Time to Minimize Cost for a Series System Sold Under Warranty”. Agriculture and Natural Resources 43 (5). Bangkok, Thailand:392-98. https://li01.tci-thaijo.org/index.php/anres/article/view/244849.