Oxford , 2000
Buku Teks
edited by Alex E. Fernandez Jilberto and Barbara Hogenboom
Routledge, 2007
Buku Teks
Pan Books, 1980
Buku Teks
World Bank
Oxford University Press, 1992
Buku Teks
Mellor, John W., author
Cornell University Press, 1966
Buku Teks