1. American Council for an Energy-Efficient Economy, Summit Blue Consulting, Vermont Energy Investment Corporation et al., 2009. Potential for energy efficiency, demand response, and onsite solar energy in Pennsylvania. http://www.aceee.org/pubs/e093.htm.
2. Air Chek, 1982, Maryland Radon information. www.md-radon.info/MD_counties.html (accessed 30.07.2009)
3. AQMD, 2006. Rule 1146.2. Emission of oxides of nitrogen from large water heaters and small boilers and process heaters, Air Quality Management District, 2005. www.aqmd.gov/rules/reg/reg11/r1146-2.pdf (accessed July 30.07.2009).
4. California Public Utilities Commission (CPUC), 2008. Database for Energy Efficient Resources, 2008. http://www.deeresources.com/.
5. CDC State, 2008. State Tobacco Activities Tracking and Evaluation (STATE) System, 2008, CDC website: www.apps.nccd.cdc.gov/StateSystem/stateSystem.aspx?selectedTopic=100&selectedMeasure=1000&dir=epi_report&ucName=ucsummary&year=2008&excel=htmlTable&submitBk=y (accessed 30.07. 2009)