Rockport Publisher, 2001
Buku Teks
Henderson, Justin, author
Hi Marketing, 2001
Buku Teks
Hickey, Lisa
Rockport Publishers, 2002
Buku Teks
Voisinet, Donald D., author
Prentice-Hall, 1983
Buku Teks
Vandika Anwari, author
2014
UI - Skripsi (Membership)