Tester, Jefferson W. (Massachusetts Institute of Technology) et al: The Future of Geothermal Energy – Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century, s. 1-9. Idaho Falls: Idaho National Laboratory, 2006. ISBN 0-615-13438-6Teoksen verkkoversio (14MB PDF) Viitattu 7.2.2007.
Tester, Jefferson W. (Massachusetts Institute of Technology) et al: The Future of Geothermal Energy – Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century. Idaho Falls: Idaho National Laboratory, 2006. ISBN 0-615-13438-6Teoksen verkkoversio (14MB PDF) Viitattu 7.2.2007.