Boyes, William J.
South Western Publishing, 1984
Buku Teks SO
Ackley, Gardner
Macmillan, 1978
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Hall, Robert Ernest
W.W. Norton, 1986
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Wachtel, Paul
McGraw-Hill , 1989
Buku Teks SO
Parkin, Michael, 1939-
Prentice-Hall, c1992
Buku Referensi