Heike Görzig: University of Hagen, Faculty for Mathematics and Computer Science, Universitätsstrasse 1, D-58097 Hagen, Germany,(E): Heike.Goerzig@fernuni-hagen.de
Holger Brocks: InConTec GmbH, Kirschenalle 7, D-96152 Burghasslach, Germany, (E): Holger.Brocks@incontec.de
Felix Engel: University of Hagen, Faculty for Mathematics and Computer Science, Universitätsstrasse 1, D-58097 Hagen, Germany, (E): Felix.Engel@fernuni-hagen.de
Tobias Vogel: University of Hagen, Faculty for Mathematics and Computer Science, Universitätsstrasse 1, D-58097 Hagen, Germany, (E): Tobias.Vogel@fernuni-hagen.de
Matthias L Hemmje: University of Hagen, Faculty for Mathematics and Computer Science, Chair of Multimedia and Internet Applications, Universitätsstrasse 1,D-58097 Hagen, Germany,(E): Matthias.Hemmje@fernuni-hagen.de
