Sánchez Machado, Inocencio Raúl, and Zulma María Ledesma Martínez. “Approach to the Measurement of Externalities in the Focusing Social Economic of Investment Appraisal”. Revista Universidad EAFIT, vol. 39, no. 131, June 2012, pp. 32-40, https://publicaciones.eafit.edu.co/index.php/revista-universidad-eafit/article/view/901.