"Outer Core" Wikipedia, the Free Encyclopedia November 21st, 2011 <http://en.wikipedia.org/wiki/Outer_core>
Pictures:
"File:Earth-crust-cutaway-english.svg" Wikipedia, the Free Encyclopedia November 21st, 2011 <http://en.wikipedia.org/wiki/File:Earth-crust-cutaway-english.svg>
Videos:
"Layers of the Earth ( High Definition )" You Tube November 21st, 2011 <http://www.youtube.com/watch?v=ukqe_6L9V54&feature=related>