Sichel, Edith
Oxford University Press, 1959
Buku Teks
Hale, John R., author
Time-Life International, 1969
Buku Teks
Durant, Will, author
Simon and Schuster, 1953
Buku Teks
Burckhardt, Jacob, author
Harper & Row Publisher, 1958.
Buku Teks
Burckhardt, Jacob, author
Harper Torchbooks, 1968
Buku Teks