Fine, Benjamin
Barron's Educational Series, 1966
Buku Referensi
Barron, Randall F.
McGraw-Hill, 1966
Buku Teks
Criscito, Pat
Barron's Educational Series, Inc., 1999
Buku Referensi
Mays, John Barrons
Longman, 1970
Buku Teks
Sharpe, Pamela J.
Barron's Educational Series, 1995
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