1. Ground heat worldwide utilization of geothermal energy;Lund;Renew Energy World,2005
2. Mands E, Sanner B. Shallow geothermal energy, 〈http://www.ubeg.de/Downloads/ShallowGeothEngl.pdf〉; 2005.
3. Geothermal Heat Pump Consortium. 〈http://www.geoexchange.org〉; 2005.
4. Kelley S. Temperatures in the Kiowa drill hole. Denver basin project—The Denver Museum of Nature Science (DMNS). 〈http://www.dmnh.org/denverbasin/r_temp.html〉; 2005.
5. On the application of the energy balance equation to predict ground temperature profiles;Mihalakakou;Sol Energy,1997