Mary Kupiec Cayton, Elliott J. Gorn, Peter W. Williams, editors
Charles Scribner's Sons, 1993
Buku Referensi
Murdoch, James
Routledge , 1926
Buku Referensi
Baron, Salo Wittmayer
Columbia University Press, 1957
Buku Teks SO
Clark, Victor S.
Peter Smith, 1949
Buku Teks SO
Toynbee, Arnold J.
Oxford University Press, 1956
Buku Teks SO