Kivaisi, A. K. “Pretreatment of Robusta Coffee Hulls and Co-Digestion With Cow-Dung for Enhanced Anaerobic Digestion”. Tanzania Journal of Science 28, no. 2 (April 19, 2021): 1–10. Accessed May 6, 2025. http://www.tjs.udsm.ac.tz/index.php/tjs/article/view/600.