1. ASHRAE handbook of HVAC applications;ASHRAE,2015
2. AHRI. ANSI/AHRI Standard 870 – 2005 Standard for performance rating of direct geoexchange heat pumps. Air-Conditioning, Heating, and Refrigeration Institute, Arlington (VA); 2009.
3. AHRI. Certified direct geo exchange certification: 870. Air-Conditioning, Heating, and Refrigeration Institute, Arlington (VA); 2011.
4. CSA. C748−13 – Performance of direct-expansion (DX) ground-source heat pumps. Canadian Standards Association, Toronto (ON); 2013.
5. Experimental determination for heat-absorbing coils buried in the earth;Coogan;Mech Eng,1949