1. H. Böni, R. Hischier, M. Lehmann, R. Zah, M., Gauch, P. Wager, Life cycle assessment of energy products: environmental impact assessment of biofuels – executive summary (only translated portion), (2007).
2. Perspectives for Biogas in Europe;Van Foreest,2012
3. A new and sound technology for biogas from solid waste and biomass;Busch;Water Air Soil Pollut. Focus,2009
4. Chapter 23–Agricultural waste management in food processing;Hansen,2013
5. Basic data of biogas;Swedish Gas Technology Centre;Phys. Radiol.,2012