1. Chowdhury, G., Chowdhury, S.: Introduction to Digital Libraries. Facet Publishing, London (2002)
2. Belkin, N.J.: Anomalous states of knowledge as a basis for information retrieval. Can. J. Inf. Sci. 5, 133–143 (1980)
3. Heaps, H.S.: Information Retrieval, Computational and Theoretical Aspects. Academic Press, Cambridge (1978)
4. Baeza-Yates, R., Ribeiro-Neto, B.: Modern Information Retrieval, vol. 463. ACM Press, New York (1999)
5. Lovins, J.B.: Development of a stemming algorithm. Mech. Trans. Comput. Linguist. 11, 22–31 (1968)