1. Section “Gastroenterology”, Second Department of Internal Diseases, Medical Faculty, Medical University—Plovdiv, 4000 Plovdiv, Bulgaria
2. Gastroenterology Clinic, University Hospital “Kaspela”, 4000 Plovdiv, Bulgaria
3. Department of Special Surgery, Medical Faculty, Medical University—Plovdiv, 4000 Plovdiv, Bulgaria
4. Surgical Department, University Hospital “Kaspela”, 4000 Plovdiv, Bulgaria
5. Department of Otorhynolaryngology, Medical Faculty, Medical University—Plovdiv, 4000 Plovdiv, Bulgaria
6. Department of Ophtalmology, University hospital “St. George”, 4000 Plovdiv, Bulgaria