1. Chicago Nasal & Sinus Center Chicago Illinois USA
2. Madison ENT & Facial Plastic Surgery New York New York USA
3. Alamo ENT Associates San Antonio Texas USA
4. Colorado ENT & Allergy Colorado Springs Colorado USA
5. Mount Sinai Hospital New York New York USA
6. Department of Otorhinolaryngology–Head and Neck Surgery University of Cincinnati College of Medicine Cincinnati Ohio USA
7. Rush University Medical Center Chicago Illinois USA
8. University of Rochester Medical Center Rochester New York USA
9. Vanderbilt University Medical Center Nashville Tennessee USA