@article {Pellens2007, title = {Conceptual Modeling of Behavior in a Virtual Environment}, journal = {Special Issue of International Journal of Product and Development}, volume = {4}, number = {6}, year = {2007}, note = {Inderscience Enterprises}, pages = {626-645}, author = {B. Pellens and O. De Troyer and F. Kleinermann and W. Bille} }