1. Praxis am Hanse-Viertel, Hamburg, Germany
2. HNO-Zentrum Rhein-Neckar, Mannheim, Germany
3. Department for Otorhinolaryngology, Head and Neck Surgery, Universitatsklinikum Mannheim II Medizinische Universitatsklinik, Mannheim, Baden-Württemberg, Germany
4. Department of Otorhinolaryngology, Head and Neck Surgery, Universitatsklinikum Erlangen, Erlangen, Bayern, Germany