Keegan, Warren J., author
Warren Keegan Associaties, 1995
Buku Teks
by Arnold de Meyer ... [and others]
John Wiley & Sons, 2005
Buku Teks
Handito Hadi Joewono, author
Pustaka Bisnis Indonesia, 2006
Buku Teks
Stalk, George Jr
The Free Press, 1990
Buku Teks
Imam Wahyudi, author
Universitas Indonesia, 2013
Artikel Jurnal