Morgan, Thomas D.
ST. Paul MInn, 1978
Buku Teks
Handler, Milton
The Foundation Press, 1967
Buku Teks
Boies, David.
Little, Brown, 1977
Buku Teks
The Foundation Press, Inc., 1975
Buku Teks
Schnitzer, Martin C.
Rand McNally College Publishing , 1978
Buku Teks