Stanojević, Bogdana, and Milan Stanojević. “Penalty Method for Fuzzy Linear Programming With Trapezoidal Numbers”. Yugoslav Journal of Operations Research 19, no. 1 (March 1, 2009): 149–156. Accessed August 25, 2025. https://yujor.erc.fon.bg.ac.rs/index.php/yujor/article/view/261.