Funk & Wagnalls Company, 1949
Buku Teks
RMIT University
Palgrave Macmillan, 2012
Buku Teks
Hampton, David R., author
McGraw-Hill, 1986
Buku Teks
Terry, George Robert, author
Learning Systems, 1981
Buku Teks
Drucker, Peter F. (Peter Ferdinand), 1909-2005, author
Harper & Brothers, 1954
Buku Teks