http://www.spartacus.schoolnet.co.uk/FWWschlieffenP.htm
http://www.yale.edu/ynhti/curriculum/units/1981/2/81.02.06.x.html
http://www.history.com/topics/french-revolution
http://inventors.about.com/library/inventors/blsteamship.htm
http://www.ciw-online.org/slavery.html
http://www.merriam-webster.com/dictionary/steamboat
http://www.history.com/topics/mexican-revolution
http://europeanhistory.about.com/od/thefrenchrevolution/ig/Pictures-from-the-French-Revolution/The-Storming-of-the-Bastille.htm
http://history1900s.about.com/od/1930s/p/greatdepression.htm
http://www.english.illinois.edu/maps/depression/about.htm
http://www.yale.edu/ynhti/curriculum/units/1981/2/81.02.06.x.html
http://www.history.com/topics/french-revolution
http://inventors.about.com/library/inventors/blsteamship.htm
http://www.ciw-online.org/slavery.html
http://www.merriam-webster.com/dictionary/steamboat
http://www.history.com/topics/mexican-revolution
http://europeanhistory.about.com/od/thefrenchrevolution/ig/Pictures-from-the-French-Revolution/The-Storming-of-the-Bastille.htm
http://history1900s.about.com/od/1930s/p/greatdepression.htm
http://www.english.illinois.edu/maps/depression/about.htm