TY - CHAP T1 - Group-Oriented Modelling Tools with Heterogeneous Semantics AU - Pinkwart, N. AU - Hoppe, H. U. AU - Bollen, L. AU - Fuhlrott, E. TI - Proceedings of the 6th International Conference on Intelligent Tutoring Systems (ITS) PY - 2002 PB - Springer Verlag IS - 2363 ER -