Books-

Altman, Linda Jacobs: Colorado : Marshall Cavendish Corporation 2011

Ayer, Eleanor & Elish, Dan: Colorado : Marshall Cavendish Corporation 2006, 1997

Thompson, Kathleen: Colorado : Marshall Cavendish Corporation 2002

Wills, Charles A. : A Historical Album of Colorado :Millbrook Press Inc. 1996

Capston Press Geography Department: Colorado : Capstone Press 1996, 1998

Miller, Amy: Colorado : Children's Press, an imprint of Scholastic Inc.

Websites-

Google.com
http://www.google.com/search?

Google Images
http://www.google.com/imghp

Wikipedia
http://en.wikipedia.org/wiki/History_of_Google

Coloradostate.weebly.com
http://coloradostate.weebly.com/index.html

Other Sources-

Flash Charts-The Fifty States:Spark Educational Publishing 2003