Artikel Jurnal
Dibenedetto, David C., author
iUniverse, Inc, 2008
Buku Teks
Wallace-Murphy, Tim, author
Watkins, 2006
Buku Teks
Rabe, Cynthia Barton, author
American Management Association, 2006
eBooks
Duhigg, Charles, author
Heinemann, 2012
Buku Teks