Mortensen, Kurt W., author
American Management Association, 2008
eBooks
Tam, Marilyn, author
Gramedia Pustaka Utama, 2007
Buku Teks
Collins, Harry, author
Cambridge University Press , 1993
Buku Teks
Jensen, Doug, author
American Management Association, 2007
eBooks
Maddi, Salvatore R., author
AMACOM, 2005
Buku Teks