1. DEPARTMENT OF GYNECOLOGY, HOSPITAL “SAINT ANNA”, MEDICAL UNIVERSITY “PROF. DR. PARASKEV STOYANOV”, VARNA, BULGARIA
2. DEPARTMENT OF GYNECOLOGY, HOSPITAL “SAINT ANNA”, MEDICAL UNIVERSITY “PROF. DR. PARASKEV STOYANOV”, VARNA, BULGARIA; RESEARCH INSTITUTE, MEDICAL UNIVERSITY PLEVEN, PLEVEN, BULGARIA
3. CLINICAL PATHOLOGY LABORATORY, MHAT “NADEZDA” WOMEN’S HEALTH HOSPITAL, SOFIA, BULGARIA; NEUROPATHOLOGICAL LABORATORY, UNIVERSITY HOSPITAL “SAINT IVAN RILSKI”, SOFIA, BULGARIA
4. DEPARTMENT OF GYNECOLOGIC ONCOLOGY, MEDICAL UNIVERSITY PLEVEN, PLEVEN, BULGARIA