United Nations, [date of publication not identified]
Buku Teks
[publisher not identified], [date of publication not identified]
Buku Teks
Wallich, Henry C., author
Harvard University Press, 1951
Buku Teks
Chavez, Joaquin Mauricio, author
Oxford University Press, 2017
eBooks
Wolfsfeld, Gadi, author
Cambridge University Press, 2003
Buku Teks