Cubillos, G., R. Arrué, D. Jeison, R. Chamy, E. Tapia, J. Rodríguez, and G. Ruiz-Filippi. “Simultaneous Effects of PH and Substrate Concentration on Hydrogen Production by Acidogenic Fermentation”. Electronic Journal of Biotechnology, vol. 13, no. 1, Jan. 2010, pp. 0-0, https://www.ejbiotechnology.info/index.php/ejbiotechnology/article/view/v13n1-6.