1. Faculty of Veterinary Medicine, Department of Pharmacology, Animal Physiology and Physiological Chemistry, Trakia University, Stara Zagora, Bulgaria
2. Faculty of Veterinary Medicine, Radioecology and Ecology Unit, Trakia University, Stara Zagora, Bulgaria
3. Faculty of Agriculture, Department of Biochemistry, Microbiology and Physics, Trakia University, Stara Zagora, Bulgaria