Doucett, Elisabeth, author
[American Management Association, ], 2008
eBooks
Naparstek, Nathan, author
Mc Graw Hill, 2006
Buku Teks
BNI Card Center, 2010
Majalah, Jurnal, Buletin
Heyel, Carl, author
American Management Association, 1960
Buku Teks
Parker, Elizabeth, author
Librarry Association , 1999
Buku Teks