Tsibizova, Ekaterina L. 2009. “The Sex and Age-Related Characteristic and the Analysis of the Natural Reasons of Death of European Bison (Bison Bonasus L.) in the Breeding Station of the Oksky Reserve”. European Bison Conservation Newsletter 2 (September):73-79. http://ojs.wisent.org/index.php/czasopismo/article/view/172.