Martin, William J., author
Brookfield, Vt., USA : Gower,, 1995.
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Martin, William J., author
Aslib Gower, 1995
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Currie, Wendy, author
John Wiley & Sons, 2000
Buku Teks
Currie, Wendy, author
John Wiley & Sons, 2000
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Dalrymple, Douglas J., author
Chichester : Wiley, Chichester : Wiley
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