1. Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences , Acad. G. Bonchev 25, 1113 Sofia , Bulgaria
2. Institute of Neurobiology, Bulgarian Academy of Sciences , Acad. G. Bonchev 23, 1113 Sofia , Bulgaria
3. Department of Analytical Chemistry, Faculty of Chemistry and Pharmacy , Sofia University “St. Kliment Ohridski” , J. Bourchier Blvd. 1, 1164 Sofia , Bulgaria
4. Biovet Ltd., Research and Development Department , 4550 Peshtera , Bulgaria