Pride, William M.
South Western Cengage Learning, 2012
Buku Teks
Madura, Jeff
South-Western College, 2001
Buku Teks
Straub, Joseph T.
Kent, 1985
Buku Teks
Cunningham, William H.
South-Western, 1984
Buku Teks
edited by Joel J. Lersier
Englewood Cliffs, N.J., Prentice-Hall
Buku Teks