https://www.khanacademy.org/humanities/renaissance-reformation/high-ren-florence-rome/leonardo-da-vinci/v/leonardo-da-vinci-last-supper-1495-98
Leonardo da Vinci by Charles Nicole
http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Leonardo.html
http://www.history.com/topics/leonardo-da-vinci
http://www.pbs.org/empires/medici/renaissance/leonardo.html
National geographic History book
Leonardo da Vinci by Charles Nicole
http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Leonardo.html
http://www.history.com/topics/leonardo-da-vinci
http://www.pbs.org/empires/medici/renaissance/leonardo.html
National geographic History book