The Conference Board; editor, Edward C. Bursk
The Free Press, 1973
Buku Teks
Northcraft, Gregory B., author
Dryden Press, 1990
Buku Teks
Kouzes, James M., author
Jossey-Bass, 2002
Buku Teks
John B. Caouette, author
John Wiley & Sons Inc, 2008
Buku Teks
Tucker, Mary, author
Prentice-Hall, 2002
Buku Teks