Arnold, Pauline
Holiday House , 1961
Buku Teks
Caffey, Andrew A.
Entrepreneur Press, 2002
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Troxell, Mary D., author
Gregg Division McGraw-Hill Book Company, 1981
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Sherman, Andrew J., author
Amacom, 1999
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Sherman, Andrew J., author
Amacom, 2011
Buku Teks