Goodall, Brian, author
Penguin Books, 1987
Buku Referensi
Whittow, John B., author
Allen Lane, 1984
Buku Referensi
G & C. Merriam Co., 1949
Buku Referensi
edited by R.J. Johnston, Derek Gregory, Geraldine Pratt, Michael Watts
Blackwell Publishing, 2000
Buku Referensi
BAKOSURTANAL, 2008
Buku Teks