1. I.C. McIlwaine , UDC in the twenty-first century. In: R. Marcella and A. Maltby (eds), The Future of Classification ( Aldershot, Gower, 2000) 93-104.
2. Classification Research Group, The need for a faceted classification as the basis of all methods of information retrieval. Originally drafted in 1955 and published in 1957, but reprinted in: A. Gilchrist (ed.), From Classification to `Knowledge Organization': Dorking Revisited or `Past is Prelude' (International Federation for Information and Documentation, The Hague, 1997 ) 1-9.