Balderas, F., E. Fernandez, C. Gómez Santillán, G. Rivera, L. Cruz-Reyes, and N. Rangel. “Uncertainty Modelling for Project Portfolio Problem Using Interval Analysis”. International Journal of Combinatorial Optimization Problems and Informatics, Vol. 7, no. 3, Nov. 2016, pp. 20-27, https://ijcopi.org/ojs/article/view/24.