A. Hotho, R. Jäschke, C. Schmitz, and G. Stumme. Proceedings of the First International Conference on Semantic and Digital Media Technologies, page 56--70. Berlin, Heidelberg, Springer-Verlag, (2006)
J. Singh. Proceedings of the 2009 Spring Simulation Multiconference, page 116:1--116:4. San Diego, CA, USA, Society for Computer Simulation International, (2009)