Schiavo-Campo, Salvatore
Winthrop Publishers, Inc., 1978
Buku Teks
Krugman, Paul R., author
Addison-Wesley , 1997
Buku Teks
Root, Franklin R., author
South-Western Publishing, 1978
Buku Teks
Root, Franklin R., author
International Thompson Publishing, 1994
Buku Teks
Gilpin, Robert, author
Princeton University Press, 1987
Buku Teks