An Ant Colony System Metaheuristic Algorithm for Solving a Bi-Objective Purchasing Scheduling Problem. - José Francisco Delgado Orta; José Antonio Coronel Hernández; Laura Cruz-Reyes; Alejandro Palacios Espinosa; Christian Ayala Esquivel; Isidro Moctezuma Cantorán; Jorge Ochoa Somuano (Res. Comput. Sci., 2014)