homepages/l/AndreasLudwig,
Andreas Ludwig, Home Page, http://www-db.informatik.uni-tuebingen.de/mitarbeiter/ludwig.shtml, University of Tübingen, Germany
homepages/l/CLiebchen,
Christian Liebchen, Home Page, http://www.math.tu-berlin.de/coga/people/liebchen/, Technical University of Berlin, Department of Mathematics, Germany
homepages/l/NorbertLuttenberger,
Norbert Luttenberger, Home Page, http://www.informatik.uni-kiel.de/comsys/kontakt-und-mitarbeiter/norbert-luttenberger/, University of Kiel, Germany