Appleyard, Dennis R., author
Irwin , 1995
Buku Teks
Salvatore, Dominick, author
Prentice-Hall, 1998
Buku Teks
Appleyard, Dennis R., author
McGraw-Hill, 2014
Buku Teks
Krugman, Paul R., author
Scott, Foresman, 1988
Buku Teks
Krugman, Paul R., author
Addison-Wesley, 2000
Buku Teks