Alpay, Olcay, and Elvan Aktürk Hayat. “Copula Approach to Select input/Output Variables for DEA”. An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 7, no. 1 (October 25, 2016): 28–34. Accessed June 5, 2025. https://ijocta.org/index.php/files/article/view/334.