Pérez-Bayer, J., R. Barrera-Zapata, and C. Salazar-Jiménez. “Effect of Colombian Coal Rank and Its Feeding Technology on Substitute Natural Gas Production by Entrained Gasification”. Revista Facultad De Ingeniería, Vol. 25, no. 41, Jan. 2016, pp. 41-53, doi:10.19053/01211129.4136.