1. Allen, J. (1987). Natural language understanding. Benjamin/Cummings Publishing Company, Inc.
2. Bruseberg, A., & Johnson, P. (2003). Understanding human error in context: Approaches to support interaction design using air accident reports. In 12th International Symposium on Aviation Psychology USA, pp. 166–171.
3. Buyko, E., Wermter, J., Poprat M., & Hahn U. (2006). Automatically adapting an NLP core engine to the biology domain. In Proceedings of the BioLink & Bio-Ontologies, SIG Meeting 2006 Brazil.
4. Chang D. and Choi K. (2006). Incremental cue phrase learning and bootstrapping method for causality extraction using cue phrase and word pair probabilities. Information Processing and Management 42(3): 662–678
5. Cole, S. V., Roya, M. D., Valtorta, M. G., & Huhns, M. N. (2006). A lightweight tool for automatically extracting causal relations from text. IEEE Xplore, 31 March 2005-2 April 2005, 125–129.