1. Venereology and Dermatologic Surgery, Onkoderma – Policlinic for Dermatology – Sofia , Bulgaria
2. Venereology and Dermatologis Surgery , Department of Dermatology – Sofia , Bulgaria
3. Department of Pathology , University Hospital “Tsaritsa Yoanna” – Sofia , Bulgaria
4. Department of Common, Abdominal and Vascular Surgery , Medical Institute of Ministry of Interior / University Hospital MVR – Sofia , Bulgaria
5. Department of Pathology , University of Virginia – Charlottesville , USA