Trotman, Kathleen M.
McGraw-Hill , 1973
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Smith, Allen N.
South-Western Pub. Co, 1986
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Pritchard, J.A.T.
The National Computing Centre, 1985
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FitzGerald, Jerry, author
Wiley, 1996
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De Vries, Mary Ann, author
Prentice-Hall, 1995
Buku Referensi