Hesseline, William B.
Louisiana State university Press, 1949
Buku Teks
Italiaander, Rolf
Prentice-Hall, 1961
Buku Teks SO
Jordan, Carl F, author
Springer, 2013
Buku Teks
Downey, Diane, author
[American Management Association, ], 2001
eBooks
Leaders Magazine,
Majalah, Jurnal, Buletin