Sawyerr, Nathaniel, Cristina Trois, Tilahun Workneh, and Vincent Okudoh. “An Overview of Biogas Production: Fundamentals, Applications and Future Research”. International Journal of Energy Economics and Policy 9, no. 2 (February 14, 2019): 105–116. Accessed December 23, 2024. https://mail.econjournals.com/index.php/ijeep/article/view/7375.