O`Malley, Michael, author
McGraw-Hill, 2012
Buku Teks
Cohen, William A.
Prentice-Hall, 1990
Buku Teks
Clemens, John, author
American Management Association, 2005
eBooks
Allen, Scott J., author
American Management Association, 2011
Buku Teks
Arvan Pradiansyah, author
Gramedia, 2005
Buku Teks