Fransiscus, Yunus, and Tuani L. Simangunsong. “Anaerobic Digestion of Industrial Tempeh Wastewater With Sludge from Cow Manure Biogas Digester As Inoculum: Effect of F M Ratio on the Methane Production”. International Journal on Advanced Science, Engineering and Information Technology, vol. 11, no. 3, June 2021, pp. 1007-13, doi:10.18517/ijaseit.11.3.11846.