Mitrevichin, Emanuil, and Lidia Sakelarieva. “Contribution to the Study of the European Ground Squirrel’s Population (Spermophilus Citellus Linnaeus, 1766) in Rila National Park, Bulgaria”. Studia Ecologiae et Bioethicae 18, no. 4 (December 21, 2020): 75–83. Accessed April 25, 2024. https://czasopisma.uksw.edu.pl/index.php/seb/article/view/7441.