CECOTA, Błażej. The Bulgarians and the Arab siege of Constantinople in 717–718. Balcanica Posnaniensia. Acta et studia, [S. l.], v. 18, p. 11–22, 2011. DOI: 10.14746/bp.2011.18.2. Disponível em: https://pressto.amu.edu.pl/index.php/bp/article/view/54639. Acesso em: 4 aug. 2026.