Gwartney, James D.
Dryden Press, 1995
Buku Teks SO
Gwartney, James D.
Harcourt Brace Jovanovich, 1990
Buku Teks SO
Gwartney, James D.
The Reyden Press, 2000
Buku Teks SO
Gwartney, James D.
Harcourt Brace Jovanovich, 1987
Buku Teks SO
Buchanan, Norman S.
Henry Holt, 1950
Buku Teks SO