Gopal, Christopher, author
Business One Irwin, 1993
Buku Referensi
Wood, Donald F., author
[American Management Association, ], 2002
eBooks
Rushton, Alan, author
Kogan Page, 2014
Buku Teks
Smykay, Edward W.
Macmillan Publishing Company, Inc., 1973
Buku Teks
Hutagaol, Budi Yanto Pargaulan, author
Fakultas Teknik Universitas Indonesia, 2011
UI - Tesis (Open)