KESSLER, W. Georgiev, Emil: Ljulka na starata i novata bŭlgarska pismenost. Südost-Forschungen, [S. l.], v. 1, n. 1, p. 475–476, 2021. Disponível em: https://www.suedost-forschungen.de/portal/index.php/sof/article/view/9968. Acesso em: 1 mai. 2025.