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Fajardo, D. , Ortiz, S. , Herrera, O. , Santis, A.. "A Comparative Analysis of Heuristics Applied to Collecting Used Lubricant Oils Generated in the City of Pereira, Colombia". World Academy of Science, Engineering and Technology, Open Science Index 120, International Journal of Transport and Vehicle Engineering, (2016), 10(12), 1548 - 1556.