Marinow, Kirył. “The Haemus Mountains As a Shelter, an Attack Outpost and an Observation Post in the Light of the Bulgarian-Byzantine Military Relations in the Early Middle Ages”. Balcanica Posnaniensia. Acta et studia 20 (January 1, 2013): 5–17. Accessed November 24, 2024. https://pressto.amu.edu.pl/index.php/bp/article/view/1725.