1. Adams, S.: Using the International Patent Classification in an online environment. World Pat. Inf. 22(4), 291–300 (2000)
2. Aslam, J.A., Montague, M.: Models for meta search. In: Proceedings of the 24th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, pp. 276–284. ACM, New York (2001)
3. Cai, L., Hofmann, T.: Hierarchical Document Categorization with Support Vector Machines. In: Proceedings of the Thirteenth ACM International Conference on Information and Knowledge Management, pp. 78–87. ACM, New York (2004)
4. Callan, J., Connell, M.: Query-based sampling of text databases. ACM Trans. Inf. Syst. 19(2), 97–130 (2001)
5. Callan, J., Lu, Z., Croft, W.B.: Searching distributed collections with inference networks. In: Proceedings of the 18th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, pp. 21–28. ACM, New York (1995)