Powell, Gary N.
Sage Publications, 1988
Buku Teks
Drucker, Peter F. (Peter Ferdinand), 1909-2005, author
Harper Colophan Books, 1977
Buku Teks
Donaldson, Gordon
Double day, 1985
Buku Teks
Warren, Robert Penn, author
The Modern Library, 1953
Buku Teks
Warren, Robert Penn
A Harvest Book, 2006
Buku Teks