1. D. Freitag: Machine Learning for Information Extraction in Informal Domains. Ph.D. thesis, Computer Science Department. Carnegie Mellon University. (1998)
2. M. E. Califf and R. Mooney.: Relational learning of pattern-match rules for information extraction. In Workshop on Natural Language Learning, ACL (1997) 9–15.
3. S. Soderland, D. Fisher, J. Aseltine, and W. Lehnert.: Crystal: Inducing a conceptual dictionary. In proceedings of IJCAI (1995) 1314–1321.
4. S. Soderland.: Learning information extraction rules for semi-structured and free text. Machine Learning, 34, (1999) 233–272.
5. J. Turmo, N. Català, and H. Rodríguez.: An adaptable IE system to new domains. Applied Intelligence, 10(2/3) (1999) 225–246.