1. Department of Clinical Oncology, Medical University of Plovdiv, Plovdiv, Bulgaria 2. Saint George University Hospital for Active Treatment, Plovdiv, Bulgaria
2. Saint George University Hospital for Active Treatment, Plovdiv, Bulgaria; First Department of Internal Disease, Medical University of Plovdiv, Plovdiv, Bulgaria
3. Specialized Hospital for Active Treatment of Hematological Diseases, Sofia, Bulgaria
4. Saint George University Hospital for Active Treatment, Plovdiv, Bulgaria