1. Raboni, M., Urbini, G.: Production and use of biogas in Europe: a survey of current status and perspectives. Rev. Ambient. Água 9(2), 191–202 (2014)
2. Biogas – An important renewable energy source. WBA fact sheet.
https://worldbioenergy.org/uploads/Factsheet%20-%20Biogas.pdf
. Accessed 27 Sept 2018
3. Rutz, D., Mergner, R., Janssen, R.: Sustainable Heat Use of Biogas Plants. A Handbook.
http://ec.europa.eu/energy/intelligent/projects/sites/ieeprojects/files/projects/documents/biogasheat_sustainable_heat_use_of_biogas_plants_en.pdf
. Accessed 27 Sept 2018
4. EBA Biogas Report 2014 is published! European Biogas Association (EBA).
http://european-biogas.eu/2014/12/16/4331/
. Accessed 27 Sept 2018
5. Shi, F.: Reactor and Process Design in Sustainable Energy Technology. Elsevier, Oxford (2014)