Jennings, Paul, author
Mizan Learning Center, 2006
Buku Teks
Ira Hermosa, author
2002
UI - Skripsi (Membership)
Artikel Jurnal
Aniq Zuhri, author
Universitas Airlangga. FISIP, 2016
Artikel Jurnal
edited by Gareth Williams, Martin Kenyon and Lynn Williams
Overseas Student Trust, 1987
Buku Referensi