Geothermal Heating and Cooling Technologies. at <http://www2.epa.gov/rhc/geothermal-heating-and-cooling-technologies#Ground>

MassDEP Geothermal Integration Fact Sheet. at <http://www.mass.gov/eea/agencies/massdep/water/reports/geothermal-integration.html>

New England Geothermal Professional Association. at <http://www.negpa.org/>

Outside the Loop . at <http://geoheat.oit.edu/otl/index.htm>