Brophy, Peter
The library in the twenty-first century : new services for the information age
Library Association Publishing, 2002
 Buku Teks SO
Statistics for the twenty-first century
edited by Florence S. Gordon and Sheldon Gordon
Mathematical Association of America, 1992
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Communication in the twenty-first century
edited by George Gerbner, Richard B. Byrne
John Wiley & Sons, 1981
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Russel, Fox Hon
Justice in the twenty-first century
Covendish Publishing Limited, 2000
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Kennedy, Paul M.
Preparing for the twenty-first century
Vintage Books, 1993
 Buku Teks SO