1. Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 25, 1113 Sofi a, Bulgaria
2. Institute of Biodiversity and Ecosystems Research, Bulgarian Academy of Sciences, 2 Gagarin Str., 1113 Sofia, Bulgaria
3. Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 103A, 1113 Sofi a, Bulgaria