1. Department of Dermatology, Venereology and Allergology, Faculty of Medicine, Medical University‒ Pleven 1, St. Kliment Ohridski Str. Pleven, 5800, Bulgaria
2. Department of Dermatology, Venereology and Allergology, Faculty of Medicine, Medical University Pleven, Bulgaria
3. Department of Obstetrics and Gynecology, Faculty of Medicine, Medical University Pleven, Bulgaria
4. Medical Diagnostic Clinical Laboratory, University Hospital“Dr. G. Stranski” Pleven, Bulgaria