Tracy, Brian, author
Amacom, 2004
Buku Teks
Tracy, Brian, author
American Management Association, 2004
eBooks
Mancini, Marc, author
McGraw-Hill, 2003
Buku Teks
Bittel, Lester Robert, author
McGraw-Hill, 1991
Buku Teks
Yager, R. Yan, author
Hannacroic Creek Book, 1999
Buku Teks