Solomon, Michael R., author
Pearson Education, 2004
Buku Teks
Soloman, Michael R.
Prentice-Hall, 1996
Buku Teks
Croft, William, author
Cambridge University Press, 2004
Buku Teks
Wadsworth, 1969, c. 1968
Buku Teks
Francis, Philip H., author
AMACOM, 1977
Buku Teks