Gilmore, Gene
Body & Fraser Publishing Company, 1997
Buku Teks SO
Baskette, Floyd K.
Macmillan, 1982
Buku Teks SO
Sharpe, Leslie T.
Camberidge University Press , 1994
Buku Teks SO
Camp, Sue C.
Glencoe/McGraw-Hill, 2001
Buku Teks SO
Camp, Sue C.
McGraw-Hill, 2001
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