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Pitman, 1935
Buku Teks
Gwartney, James D., author
The Reyden Press, 2000
Buku Teks
Buchanan, Norman S., author
Henry Holt, 1950
Buku Teks
Gwartney, James D.
FL. The Dryden Press, 1995
Buku Teks
Gwartney, James D.
Harcourt Brace Jovanovich, Publisher, 1987
Buku Teks