Heckelei, Thomas, Wolfgang Britz, and Yinan Zhang. “Positive Mathematical Programming Approaches – Recent Developments in Literature and Applied Modelling”. Bio-based and Applied Economics 1, no. 1 (March 23, 2012): 109–124. Accessed May 6, 2024. https://oaj.fupress.net/index.php/bae/article/view/3221.