M. Sutaone, P. Bartakke, V. Vyas, and N. Pasalkar. TENCON 2003. Conference on Convergent Technologies for Asia-Pacific
Region, 1, page 235--238. IEEE Computer Society, (2003)
J. Väyrynen, T. Honkela, and L. Lindqvist. Proceedings of the Workshop Semantic Content Acquisition and Representation (SCAR), Stockholm, Sweden, Swedish Institute of Computer Science, (2007)SICS Technical Report T2007-06.