Merchant, Charles J.
Harper & Row, 1971
Buku Teks
Gager, William A.
Macmillan, 1968
Buku Teks
Gallian, Joseph A.
D.C. Heath, 1990
Buku Teks
Griswold, Alice L.
Holt, Rinehart and Winston, 1961
Buku Teks
Hungerford, Thomas W.
Thomson and Brooks/cole, 2005
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