1. Cimiano, P., Haase, P., Heizmann, J.: Porting Natural Language Interfaces Between Domains: an Experimental User Study with the ORAKEL System. In: Proc. 12th International Conference on Intelligent User Interfaces, Honolulu, Hawaii, USA, pp. 180–190 (2007)
2. BBC News. Bill Gates Says: Mouse is Out, Touch Screen and Natural Language Interface Are In, http://news.bbc.co.uk/player/nol/newsid_7170000/newsid_7174300/7174330.stm?bw=bb&mp=wm&asb=1&news=1&bbcws=1
3. ELF Software, http://www.elf-software.com/FaceOff.htm
4. DARPA Air Travel Information System (ATIS0), http://www.ldc.upenn.edu/Catalog/readme_files/atis/sdtd/trn_prmp.html
5. Lecture Notes in Artificial Intelligence;R.A. Pazos R.,2005