1. Energy (SICs: 4911, 4920), Encyclopedia of Global Industries, Online edition, Thomson Gale, 2006
2. Edison Electric Institute, Statistical Yearbook of the Electric Utility Industry 1999, Washington, DC, 2000
3. Energy Information Administration, Electric Power Annual 1999, vol. II, DOE/EIA-0348 (99)/2, Washington, DC, 2000
4. Energy Information Administration, Annual Energy Review 2004, DOE/EIA-0348, Washington, DC, 2005
5. Understanding Electric Power Systems;Casazza,2003