1. A Literature Search on Hydroelectric Power in South America. Retrieved November 24, 2008, from lilt.ilstu.edu Web site: http://lilt.ilstu.edu/psanders/litsearch/hydroelectric.htm

2. Cruel Oil, how palm oil harms health, rainforests and wildlife. Retrieved November 24, 2008, from www.cspinet.org Web site: http://www.cspinet.org/palm/

3. Estimating the Net Energy Balance of Corn Ethanol. Retrieved November 24, 2008, from www.ethanol-gec.org Web site: http://www.ethanol-gec.org/corn_eth.htm

4. Geothermal Energy, Energy from the Earth\'s Core. Retrieved November 24, 2008, from Energy Kids Page Web site: http://www.eia.doe.gov/kids/energyfacts/sources/renewable/geothermal.html

5. Hydroelectric Power: How it works. Retrieved November 24, 2008, from ga.water.usgs.gov Web site: http://ga.water.usgs.gov/edu/hyhowworks.html

6. Solar cells. Retrieved November 24, 2008, from HowStuffWorks.com Web site: http://science.howstuffworks.com/solar-cell2.htm added: December 6, 2008

7. Tidal Power. Retrieved November 24, 2008, from alternative-energy-news.info Web site: http://www.alternative-energy-news.info/technology/hydro/tidal-power/