Carpendale, Jeremy, author
Blackwell Publishing, 2006
Buku Teks
Artikel Jurnal
Lawson, Joseph W.R., II, author
American Management Association, 1998
eBooks
Gronlund, Norman E.
Allyn and Bacon, 1995
Buku Teks
edited by Deborah Chapman
Chapman & Hall, 1992
Buku Teks