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<referencetext xmlns="http://eprints.org/ep2/data/2.0">Mr Slobodanka Todorović: Stručna klasifikacija po sistemu UDK: u lisnom i elektronskom katalogu, Narodna biblioteka Srbije, Beograd, 2001.

I. C. McIlwaine: The universal Decimal Classification: a guide to its use, UDC Consortium, Hague, 2000

Extensions and Corrections to the UDC, UDC Consortium, Hague, 1995.

Extensions and Corrections to the UDC, UDC Consortium, Hague,1996</referencetext>
