Cambridge University Press, 1997
eBooks
Burns, James McGregor, author
Prentice-Hall, 1963
Buku Teks
Peirce, Neal R.
W. W. Norton, 1983
Buku Teks
Neal, Harry Edward, author
Julian Messner, 1967
Buku Teks
Hall, J. Oliver, author
America Book Company, 1958
Buku Teks