1. Biogas anaerobic digester considerations for swine farms in North Carolina;Westerman,2008
2. Pilot project of biogas production from pig manure and urine mixture at ambient temperature in Ventanilla (Lima, Peru);Ferrer;Waste Manag,2009
3. Lüer M, editor. Installation manual for low-cost polyethylene tube digesters; 2010. Retrieved November 26, 2012 from 〈https://energypedia.info/images/1/19/Low_cost_polyethylene_tube_installation.pdf〉.
4. Life cycle thinking assessment applied to three biogas projects in central Uganda [thesis];Ocwieja,2010
5. Biogas-application and product development;Kossmann,1999