by the Economist Intelligence Unit and the Cartographic Dept. of the Clarendon Press
Oxford University Press, 1956
Buku Referensi
Turnock, David
Routledge, 1997
Buku Teks
Wellisz, Stanislaw, author
McGraw-Hill, 1966
Buku Teks
Kitzinger, Uwe W., author
Frederick A. Praeger, 1963
Buku Teks
Routledge, 1998
Buku Teks