Банік, М. В. “Some Aspects of Relationships of Two Subspecies of the Common Stonechat (Saxicola Torquata) in Northern Caucasus”. The Journal of V.N.Karazin Kharkiv National University. Series «Biology», Vol. 25, 1, pp. 137-44, https://periodicals.karazin.ua/biology/article/view/5571.