Weiss, John, author
Prentice-Hall, 1995
Buku Teks
Akin, John S., author
World Bank, 1987
Buku Teks
Wibbels, Erik, author
Cambridge University Press, 2005
Buku Teks
by R.I. Downing ... [and others]
Melbourne University Press , 1964
Buku Teks
Taft, Philip, author
Rinehart, 1950
Buku Teks