6Carton J. Hayes, Parker Thomas Moon & John W. Wayland, World History, p. 417.
7Carlo M. Cipolla, Gun, Sails, & Empires : Technological Innovation and the Early Phases of European Expansion, 1400-1700, New York: Pantheon Books, 1965.
8Edward Potts Cheyney, European Background of American History, 1300-1600, New York: Frederick Ungar Publishing Co. , 1966.
9Carton J. Hayes, Parker Thomas Moon & John W. Wayland, World History, New York: The Macmillan Company, 1934.
10James Edward Gillespie, A History of Modern Europe, 1500-1815, New York, 1939.
