Artikel Jurnal
Marker, Jamseed, author
McFarland, 2003
Buku Teks
Jolliffe, Jill
University of Queensland, 1978
Buku Teks
Rudy Aquila Nugraha, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2005
UI - Skripsi (Membership)
Singh, Bilveer, 1956-, author
Geo-Strategic Analyses, 1998
Buku Teks