Sources
3- Egré, Dominique; Milewski, Joseph (2002). "The diversity of hydropower projects".
4- Hill, Donald (2013). A History of Engineering in Classical and Medieval Times.
5- Bartle, Alison (2002). "Hydropower potential and development activities".
8- "Energy Sources: Solar". Department of Energy.
10- Office of ENERGY EFFICIENCY & RENEWABLE ENERGY
11- Energysage
12- Windustry.org