1. Linking Heat and Electricity Systems. Co-Generation and District Heating and Cooling Solutions for a Clean Energy Future (IEA Publishing, Paris, 2014).
2. https://eu-smartcities.eu/sites/all/files/Smart%20Thermal%20Grids%20-%20Smart%20Cities%20Stakeholder%20Platform.pdf.
3. http://www.stw-crailsheim.de/stadtwerke-crailsheim/top-themen/projekt-solaranlage.html.
4. http://dbdh.dk.
5. http://www.ens.dk/.