Rogers, Everett M., author
Free Press, 1994
Buku Teks
Tosh, John, author
Longman , 1991
Buku Teks
Australian : Bridge Printery Pty
Majalah, Jurnal, Buletin
Wade, H. W. R.
Clarendon Press, 1971
Buku Teks
Schwartz, Bernard, author
Little, Brown & Co., 1991
Buku Teks