Johns Hopkins University, Baltimore, Maryland, United States
Ear, Nose, and Throat Associates of South Florida, Boca Raton, Florida, United States
Tower ENT, Los Angeles, California, United States
St. Joseph-Stift, Bremen, Germany
G.B. Morgagni- L. Pierantoni Hospital, Forli, Italy
Advanced Sleep Research, Berlin, Germany
Clinique Univ. Saint-Luc, Brussels, Belgium