University of Cologne, Dept. of Psychiatry and Psychotherapy, Cologne, NRW, Germany
University of Tuebingen, Dept. of Dermatology, Tuebingen, BW, Germany
University of Cologne, Dept. of Dermatology, Cologne, NRW, Germany
Dpt. of Dermatology, University of Hannover, Hannover, Germany
Dpt. of Dermatology, Humboldt University, Berlin, Germany
Dept. of Dermatology, Elbe Klinikum, Buxtehude, Germany
Dpt. of Dermatology, University of Frankfurt, Frankfurt/Main, Germany
Dpt. of Dermatology, University of Cologne, Koeln, Germany
Dpt. of Dermatology; UK-SH Campus Kiel, Germany, Kiel, Germany
Helios Klinikum Emil von Behring GmbH, Berlin, Germany
Specialized Hospital for Active Treatment of Pulmonary Diseases "Sveta Sofia", Sofia, Bulgaria
Karl-Hansen-Klinik, Bad Lippspringe, Germany
Atlanta Gastroenterology Associates, Atlanta, Georgia, United States
South Denver Gastroenterology, Englewood, Colorado, United States
University of Florida, Gainesville, Florida, United States
1st Dept. of Medicine, Cologne University Hospital, Cologne, Germany
University of Cologne, Cologne, Germany
University of Cologne, Cologne, Germany
University of Dresden, Dresden, Germany
University of Kiel, Kiel, Germany
Department of Psychiatry University Cologne, Cologne, North Rhine-Westphalia, Germany