Ellsworth, P.T.
Macmillan, 1975
Buku Teks
Bhagwati, Jagdish
MIT Press, c1991
Buku Teks
Balaam, David N., 1950-
Pearson Education, 2014
Buku Teks
Balaam, David N., 1950-
Pearson/Prentice Hall, 2005
Buku Teks
Vernon, Raymond
Prentice-Hall, 1996
Buku Teks