1. Division of Palaeobotany and Palynology, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria
2. Department of Archaeology, Regional History Museum of Rousse, Rousse, Bulgaria
3. Division of Ecological Classification and Freshwater Ecosystems, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria
4. Division of Biodiversity and Ecology of Invertebrates, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria
5. Department of Veterinary Anatomy, Histology and Embryology, Trakia University of Stara Zagora, Stara Zagora, Bulgaria