Lindesay, Vane
Oxford university press, 1983
Buku Teks
Lee, Newton, author
Springer, 2012
eBooks
Lurie, Morris, author
Penguin Books, 1985.
Buku Teks
Qualman, Erik, author
Wiley, 2009
Buku Teks
Marshall, Edward M.
American Management Association, 1995
Buku Teks