1. Knapp, M., Hall, J.: Nonverbal Communication in Human Interaction, 4th edn. Harcourt Brace College Publishers (1997)
2. Fabri, M., Moore, D., Hobbs, D.: Expressive agents: Non-verbal communication in collaborative virtual environments. In: Proceedings of Autonomous Agents and Multi-Agent Systems, Bologna, Italy (2002)
3. Swartout, W., Hill, R., Gratch, J., Johnson, W., Kyriakakis, C., Labore, K., Lindheim, R., Marsella, S., Miraglia, D., Moore, B., Morie, J., Rickel, J., Thiebaux, M., Tuch, L., Whitney, R.: Toward the holodeck: Integrating graphics, sound, character and story. In: Proceedings of 5th International Conference on Autonomous Agents, Montreal, Canada (2001)
4. Durlach, N., Slater, M.: Presence in shared virtual environments and virtual togetherness. In: BT Workshop on Presence in Shared Virtual Environments, Ipswich, UK (1998)
5. Cassell, J., Vilhjálmsson, H., Chang, K., Bickmore, T., Campbell, L., Yan, H.: Requirements for an architecture for embodied conversational characters. In: Magnenat-Thalmann, N., Thalmann, D. (eds.) Computer Animation and Simulation 1999, pp. 109–120. Springer, Vinna (1999)