1. Acibadem City Clinic UMHAT, Sofia, Bulgaria
2. Department of Neurology, UMHAT “Alexandrovska”, Neurology Clinic, Medical University Sofia, Sofia, Bulgaria
3. Bulgarian Academy of Sciences, Sofia, Bulgaria
4. Department of Internal medicine, UMHAT “Alexandrovska”, Cardiology Clinic, Medical University Sofia, Sofia, Bulgaria
5. Department of Clinical Laboratory and Drug Toxicity, UMHAT “Alexandrovska” Clinical laboratory, Medical University Sofia, Sofia, Bulgaria
6. Department of Health Care, UMHAT “Medica Cor”, Ruse, University of Ruse “Angel Kanchev”, Ruse, Bulgaria