http://www.academicamerican.com/progressive/topics/progressive.html
http://www.history.com/topics/industrial-revolution
http://millercenter.org/president/mckinley/essays/biography/2
http://www.sparknotes.com/testprep/books/sat2/history/chapter12section1.rhtml
http://www.step.org/publications/leaflets/trusts_explained.aspx
http://www.whitehouse.gov/about/presidents/williammckinley
http://history1900s.about.com/od/1900s/qt/mckinleykilled.htm
http://www.brainyquote.com/quotes/authors/t/theodore_roosevelt.html
http://www.theodoreroosevelt.org/life/conservation.htm
http://www.history.com/topics/industrial-revolution
http://millercenter.org/president/mckinley/essays/biography/2
http://www.sparknotes.com/testprep/books/sat2/history/chapter12section1.rhtml
http://www.step.org/publications/leaflets/trusts_explained.aspx
http://www.whitehouse.gov/about/presidents/williammckinley
http://history1900s.about.com/od/1900s/qt/mckinleykilled.htm
http://www.brainyquote.com/quotes/authors/t/theodore_roosevelt.html
http://www.theodoreroosevelt.org/life/conservation.htm