@inproceedings{TUC-CSCW/PHBF02, author = "N. Pinkwart and H. U. Hoppe and L. Bollen and E. Fuhlrott", title = "Group-Oriented Modelling Tools with Heterogeneous Semantics", year = 2002, booktitle = "Proceedings of the 6th International Conference on Intelligent Tutoring Systems (ITS)", publisher = "Springer Verlag", number = 2363 }