Credits 2

http://palaeolimnologypetroleumrrr.weebly.com/pros-and-cons.html

Credits 2

http://energyinformative.org/hydroelectric-energy-pros-and-cons/

http://www.eia.gov/kids/energy.cfm?page=hydropower_home-basics

http://www.eia.gov/kids/energy.cfm?page=coal_home-basics

http://debate.yukozimo.com/pros-and-cons-of-coal-energy/