Leach, Steve
Macmillan Presss, 1994
Buku Teks
Longman, 1990
Buku Teks
Elcock, Howard, author
Routledge, 1994
Buku Teks
Rebekka Megasari, author
2016
UI - Tesis (Membership)
Muhammad Manar Barmawi, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2010
UI - Tesis (Open)