1. A Policy Framework for Climate and Energy in the Period from 2020 to 2030. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions,2014
2. 767 Final/2, Proposal for a Directive of the European Parliament and of the Council on the Promotion of the Use of Energy from Renewable Sources (Recast);COM,2016
3. EBA Statistical Report 2018;European Biogas Association,2018
4. Review on research achievements of biogas from anaerobic digestion;Mao;Renew. Sustain. Energy Rev.,2015
5. The State of Renewable Energies in Europe;EurObserv’ER Report,2018