1. Center for Rhinology and Allergology; Wiesbaden Germany
2. Department of Otorhinolaryngology; University Hospital Schleswig-Holstein; Lübeck Germany
3. Rhinology Unit and Smell Clinic; Department of Otorhinolaryngology; Hospital Clinic; IDIBAPS; Universitat de Barcelona, CIBERES; Barcelona Catalonia Spain
4. Department of Otorhinolaryngology; University Hospitals Leuven; Leuven Belgium
5. Department of Otorhinolaryngology; Academic Medical Centre; Amsterdam The Netherlands
6. Department of Otolaryngology; National University of Singapore; Singapore
7. Department of Otorhinolaryngology; Ghent University; Ghent Belgium