1. Climate change 2007: synthesis report, contribution of working groups I, II and III to the fourth assessment report of the intergovernmental panel on climate change;IPCC,2007
2. Agenda 21. United Nations conference on environment and development;UN,1992
3. Proceedings of the European conference on sustainable cities & towns;Charter of European Cities & Towns Towards Sustainability,1994
4. C40Cities. C40Cities: an introduction. 2010; http://www.c40cities.org/.
5. European Commission. Covenant of Mayors. 2010; http://www.eumayors.eu/.