Zhang, Hongqiong, Wenzhe Li, Yong Sun, and Xiangyou Wang. 2014. “Enhancement of Biogas Production in Two-Phase Anaerobic Fermentation System for Lower-Temperature Applications”. Journal of Technology Innovations in Renewable Energy 3 (3):120-28. https://doi.org/10.6000/1929-6002.2014.03.03.5.