Nguyen, Thanh. “Approximation Schemes for Two Non-Linear Knapsack Problems and Their Applications in Alternating Current Electric Systems”. Journal of Computer Science and Cybernetics 33, no. 2 (December 29, 2017): 165–179. Accessed May 4, 2024. https://vjs.ac.vn/index.php/jcc/article/view/10673.