Morrisey, George L., author
Prenhallindo, 1997
Buku Referensi
Rue, Leslie W., author
McGraw-Hill Publishing Company, Ltd., 1989
Buku Teks
Kaufman, Roger A.
Prentice-Hall, 1972
Buku Teks
Johnston, Robert E., author
American Management Association, 2003
eBooks
Johnston, Robert E., author
American Management Association;, 2013
eBooks