Maton, Kenneth I., author
Oxford University Press, 2016
eBooks
United Nations, 2007
Buku Teks
Herring, E. Pendleton, author
McGraw-Hill, 1936
Buku Teks
Schultze, Charles L., author
The Brookings Institution, 1977
Buku Teks
Wirtz, W. Willard, author
Harper & Row, 1964
Buku Teks