New York: W.W.Norton & Company, 1988,
Buku Referensi
Sitkoff, Harvard, author
Oxford University Press, 2000
Buku Teks
ECAM Publications, 1989
Buku Teks
Canfield, Leon H., author
Houghton Mifflin, 1954
Buku Teks
Risjord, Norman K., author
Prentice-Hall, 1985
Buku Teks