McQuaig, Douglas J.
Houghton Mifflin, 1989
Buku Teks
Carlson, Arthur E., author
South Western, 1986
Buku Teks
Heintz, James A., author
Thomson/South-Wester, 2005.
Buku Teks
Heintz, James A., author
South-Western Publishing, 1990
Buku Teks
Carlson, Arthur E., author
South-Western Publishing , 1982
Buku Teks