1. Institute for Visualization and Interactive Systems, University of Stuttgart, Stuttgart, Germany and Human-Computer Interaction Institute, Carnegie Mellon University, Pittsburgh, PA, USA
2. Institute for Visualization and Interactive Systems, University of Stuttgart, Stuttgart, Germany; Vrije Universiteit Amsterdam, Amsterdam, Netherlands and Eindhoven University of Technology, Eindhoven, Netherlands
3. Institute for Visualization and Interactive Systems, University of Stuttgart, Stuttgart, Germany and University of Regensburg, Regensburg, Germany
4. Institute for Natural Language Processing, University of Stuttgart, Stuttgart, Germany
5. University of Stuttgart, Stuttgart, Germany
6. Institute for Visualization and Interactive Systems, University of Stuttgart, Stuttgart, Germany and Eindhoven University of Technology, Eindhoven, Netherlands