RAMIREZ, I. D.; RAMÍREZ VILLAREAL, A.; OSPINA NIETO, J. D. Modeling and nonlinear control of volatile fatty acids in an upflow anaerobic fixed bed biofilm reactor (UAFBR). Revista Ingenierías Universidad de Medellín, v. 19, n. 36, p. 53-69, 9 Jul. 2019.