Harvard Bussiness School Press, 1990
Buku Teks
Underhill, Brian O., author
Berrett-Koehler Publishers, Inc., 2007
Buku Teks
Matthews, Lawrence M., author
McGraw-Hill , 1983
Buku Teks
Dale, Margaret, author
Gramedia, 2003
Buku Teks
Lendrum, Tony, author
McGraw-Hill, 1995
Buku Referensi