London Health Sciences Centre Research, London, Ontario, Canada
State Hospital of Traumatology and Orthopaedics, Riga, Latvia
Daugavpils Pilsetas Centrala Slimnica, Daugavpils, Latvia
Alabama Nasal & Sinus Center, Birmingham, Alabama, United States
Northwestern University Medical Center, Department of Otolaryngology, Chicago, Illinois, United States
Cleveland Nasal Sinus & Sleep, Cleveland, Ohio, United States