Blodgett, Ralp H., author
New York, N.Y. Rinehart & Co 1951,
Buku Teks
Case, Karl E., author
Pearson, Prentice Hall, 2009
Buku Teks
Mankiw, N. Gregory, author
Harcout College, 1998
Buku Teks
Case, Karl E., author
Prentice-Hall, 2004
Buku Teks
Case, Karl E., author
Prentice-Hall, 1996
Buku Teks