Boev, Zlatozar. “European Bison (Bison Bonasus Linnaeus, 1758) in Bulgaria: Fossil and Historical Records, Distribution, and Disappearance”. Journal of Wildlife and Biodiversity 6, no. Suppl. 1 (July 17, 2022): 92–99. Accessed April 27, 2024. https://wildlife-biodiversity.com/index.php/jwb/article/view/198.