1. Department of Dermatology, University of Mainz, Mainz, Germany
2. Dermatologikum Hamburg, Hamburg, Germany
3. Venenzentrum Leipzig, Leipzig, Germany
4. Gemeinschaftspraxis Nürnberg, Nuremberg, Germany
5. Hospital St Michel, Paris, France
6. Centre Hospitalier Universitaire Service de Chirurgie Vasculaire, Grenoble, France
7. Clinique Ambroise Paré, Nancy, France