1. Commercial/Institutional Ground-Source Heat Pump Engineering Manual;ASHRAE,1995
2. C.S. Gilbreath, Hybrid ground-source heat pump systems for commercial applications, Master's Thesis, University of Alabama, Tuscaloosa, Alabama, 1996.
3. Ground-source Heat Pumps: Design of Geothermal Systems for Commercial and Institutional Buildings;Kavanaugh,1997
4. A design method for hybrid ground-source heat pumps;Kavanaugh;ASHRAE Transactions,1998
5. Performance of a hybrid ground-coupled heat pump system [J];Phetteplace;ASHRAE Transactions,1998