Burke, D. Barlow
The Michie Company, 1993
Buku Teks
Lewis, Stephen
Oxford University Press, 1984
Buku Teks
Solomon, Eldra Pearl
Saunders College, 1995
Buku Teks
Solomon, Michael R.
Pearson Education, 2004
Buku Teks
Soloman, Michael R.
Prentice-Hall, 1996
Buku Teks