Washio, S., S. Yamada, T. Tanaka, and T. Tanino. “PARETO-EFFICIENT TARGET BY OBTAINING THE FACETS OF THE EFFICIENT FRONTIER IN DEA”. Journal of Nonlinear Analysis and Optimization: Theory & Applications, vol. 2, no. 1, Dec. 2011, pp. 211-24, http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/20.