URL's
http://en.wikipedia.org/wiki/Leonardo_da_Vinci
http://www.leonardodavinci.net/
http://www.sparknotes.com/biography/davinci/section1.rhtml
http://www.leonardoda-vinci.org/biography.html
http://www.leonardo-da-vinci-biography.com/leonardo-da-vinci-inventions.html
http://www.leonardodavinci.net/
http://www.sparknotes.com/biography/davinci/section1.rhtml
http://www.leonardoda-vinci.org/biography.html
http://www.leonardo-da-vinci-biography.com/leonardo-da-vinci-inventions.html