Schwartz, Bernard, author
McGraw-Hill, 1971
Buku Teks
Toynbee, Arnold J., author
Oxford University Press, 1956
Buku Teks
Murdoch, James, author
Routledge , 1996
Buku Referensi
McKay, John P., author
Houghton Miffiln, 1984
Buku Teks
Mary Kupiec Cayton, Elliott J. Gorn, Peter W. Williams, editors
Charles Scribner's Sons, 1993
Buku Referensi