Federal Department of Foreign Affairs FDFA, 2007
Buku Referensi
Council of Europe
Martinus Nijhoff Publishers, 1990
Buku Referensi
Selby, David, author
Cambridge University Press, 1988
Buku Teks
Unesco, 1970
Buku Teks
edited by Ian Brownlie, Guy S. Goodwin-Gill
Clarendon Press, 1971
Buku Teks