Milner, Richard
Facts On File, 1990
Buku Referensi
Pastoureau, Michael
London Thames and Hudson 1997
Buku Teks
Sellery, G. C.
Madison: University of Wisconsin Press, 1950
Buku Teks
Kelly, Alfred H., author
W.W Norton & Company Inc., c 19
Buku Teks
Kelly, Alfred H., author
W.W. Norton & Company. Inc., 1963
Buku Teks