Nixon, Richard
Warner Books, 1982
Buku Teks SO
Harvard Bussiness School Press, 1990
Buku Teks SO
Blanchard, Kenneth H.
Bareett-Koehler, 2012
Buku Teks SO
North Corolina : The American Biographical Institute, 1986,
Buku Referensi
Hesseline, William B.
Louisiana State university Press, 1949
Buku Teks SO