http://en.wikipedia.org/wiki/Hydroelectricity

http://www.answers.com/topic/hydroelectricity

http://www.epa.gov/cleanenergy/energy-and-you/affect/hydro.html

http://www.newworldencyclopedia.org/entry/Hydroelectricity

http://www.electricityforum.com/hydroelectricity.html

http://library.thinkquest.org/26366/text/alternative/hydro.html

http://www.wordiq.com/definition/Hydroelectricity

http://www.sciencedaily.com/articles/h/hydroelectricity.htm

http://www.bookrags.com/Hydroelectricity

http://www.juliantrubin.com/encyclopedia/renewable_energy/hydroelectricity_advantages.html