Gamiye Bouh, I. ., M. Z. . Alam, N. . Ahmed Kabbashi, and A. . Mohamed Ali. “Enhancement of Biogas Production from Sewage Sludge by Biofilm Pretreatment Method”. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, vol. 57, no. 2, Dec. 2020, pp. 141-7, https://www.akademiabaru.com/submit/index.php/arfmts/article/view/2543.