Brown, J. F.
Frederick A. Preager, 1966
Buku Teks
Brabandere, Luc de
Random House, 2013
Buku Teks
Westview Press, 1989
Buku Teks
Westview Press, 1989
Buku Teks
by the Economist Intelligence Unit and the Cartographic Dept. of the Clarendon Press
Oxford University Press, 1956
Buku Referensi