1. Belkin N.J.: Anomalous states of knowledge as a basis for information retrieval. Can. J. Inform. Sci. 5, 133–143 (1980)
2. Campbell, I.: Supporting information needs by ostensive definition in an adaptive information space. In: MIRO’95. Electronic Workshops in Computing. Springer, Berlin (1995)
3. Campbell I.: Interactive evaluation of the ostensive model, using a new test-collection of images with multiple relevance assessments. J. Inf. Retriev. 2(1), 89–114 (1999)
4. Campbell, I., Rijsbergen, C.J.V.: Ostensive model of information needs. In: Proceedings of the Second International Conference on Conceptions of Library and Information Science: Integration in Perspective (CoLIS 2), pp. 251–268 (1996)
5. Crouch, C.J., Apte, S., Bapat, H.: An approach to structured retrieval based on the extended vector model. In: Proceedings of INEX 2003 Workshop, pp. 89–93. Germany, December (2003)