Hagan, Frank E., author
Nelson-Hall, 1989
Buku Teks
Schwartz, Martin D., author
Anderson , 2003
Buku Teks
Barlow, Hugh D.
Litle, Brown and Company, 1984
Buku Teks
Champion, Dean J., author
Pearson/Prentice Hall, 2006
Buku Teks
Taylor, Ian R., author
Routledge, 1994
Buku Teks