Harrigan, John J.
Little, Brown, 1984
Buku Teks SO
Dye, Thomas R.
Prentice-Hall, 1988
Buku Teks SO
Saywell, John J.
University of Toronto Press , 1957
Buku Teks
Palumbo, Dennis J.
Harcourt Brace College, 1994
Buku Teks SO
Laski, Harold J.
George Allen and Unwin, 1960
Buku Teks SO