O`Neil, Robert
Avon Books, 1978
Buku Teks
Liff, Stewart, author
American Management Association;, 2010
eBooks
Rivkin, Robert S.
Discus Books/Published By Avon, 1972
Buku Teks
Malin, Martin H., author
Thomson/West, 2011
Buku Teks
Carliner, David
Avon Books, 1977
Buku Teks