S. Wahyuni, S. H. Sutjahjo, Y. A. Purwanto, A. M. Fuah, and R. Kurniawan, “The Model of Biogas Utilization from Livestock Manure Using Farmer Group Approach to Meet Alternative Energy at Household Scale”, IJSBAR, vol. 43, no. 1, pp. 57–66, Jan. 2019.