Dingus, Lowell, author
Carlton, 2012
Buku Referensi
Lamb, Harold, author
Doubleday, 1955
Buku Teks
Harris, Jim, author
[American Management Association, ], 1999
eBooks
Gerzon, Robert
Bantam Books , 1998
Buku Teks
Awbrey, David S.
Little, Brown Company, 1999
Buku Teks