Walters, Martin
Miles Kelly, 2000
Buku Referensi
Feduccia, Alan, author
Yale University Press, 1999
Buku Teks
Sembiring, Timur, author
Fakultas Ilmu Sosial dan Ilmu Politik Universitas Indonesia, 2006
UI - Tesis (Membership)
Cayley, Neville W., author
Angus and Robertson, 1931
Buku Teks
Castro, Brian
George Allen and Unwin, 1983
Buku Teks