The Cow - A Manual how to build a micro anaerobic digester: https://wickcuriosityshop.net/2016/01/18/160118_A_COW_MANUAL_digital_copy-01.pdf
Biogas and How to Make a DIY Anaerobic Digester: https://www.treehugger.com/renewable-energy/biogas-and-how-to-make-a-diy-anaerobic-digester-video.html