LESZKA, Mirosław J. Nicholas Mystikos, patriarch of Constantinople in the light of his letters to Simeon, ruler of Bulgaria. Balcanica Posnaniensia. Acta et studia, [S. l.], v. 18, p. 23–34, 2011. DOI: 10.14746/bp.2011.18.3. Disponível em: https://pressto.amu.edu.pl/index.php/bp/article/view/54640. Acesso em: 6 aug. 2026.