OBrien, Jack
Kiplinger Books, 1999
Buku Teks
Rudan, Gina Amaro, author
Simon and Schuster, 2011
Buku Teks
Green, Charles H., author
McGraw-Hill , 2012
Buku Teks
Jensen, Doug, author
American Management Association, 2007
eBooks
Sparta, Kelle, author
American Management Association, 2006
eBooks