1. Department of Prosthetic Dentistry, Faculty of Dental Medicine, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
2. Department of Healthcare Management, Faculty of Public Health, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
3. Department of Medical Informatics, Biostatistics and eLearning, Faculty of Public Health, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria