www.bbc.co.uk/schools/primaryhistory/.../christopher_columbu.
encyclopedia.kids.net.au/page/cr/Cristoforo_Colombo
https://it.wikipedia.org/wiki/Galileo_Galilei
www.bbc.co.uk/history/historic_figures/galilei_galileo.shtml
https://it.Wikipedia.org/wiki/amerigo_Vespucci
https://it.m.Wikipedia.org/wiki/amerigo_vespuc ci_(a_5312)
http://www.softschools.com/facts/biography/amerigo_vespucci_facts/843/
encyclopedia.kids.net.au/page/cr/Cristoforo_Colombo
https://it.wikipedia.org/wiki/Galileo_Galilei
www.bbc.co.uk/history/historic_figures/galilei_galileo.shtml
https://it.Wikipedia.org/wiki/amerigo_Vespucci
https://it.m.Wikipedia.org/wiki/amerigo_vespuc ci_(a_5312)
http://www.softschools.com/facts/biography/amerigo_vespucci_facts/843/