Sage Publications, 1982
Buku Teks
International Bank for Reconstruction and Development ; editor, Francis Adams Truslow
John Hopkins Press, 1953
Buku Teks
Erisman, H. Michael, author
Westview Press, 1985
Buku Teks
Ibrahim l.
N.V. Kemudi, 1959
Buku Teks
Yglesias, Jose
Pantheon Books, 1968
Buku Teks