1. Report of President of Energy Regulatory Office – Heat in Numbers http://www.ure.gov.pl/portal/pl/pdb/509/Energetyka_cieplna_w_liczbach.html (in Polish).
2. Maximal utilisation of the market forces in the heat sector;Elleriis;News from DBDH-Danish Board of District Heating,2003
3. Stockholm CHP potential-An opportunity for CO2 reductions?;Danestig;Energy Policy,2007
4. http://www.statkraftvarme.no. District heating system in Trondheim
5. http://desire.iwes.fraunhofer.de/online_germany.htm. District heating system in Schwäbische Hall