GRZESIK, Ryszard. Christianization of Bulgaria and Great Moravia – parallelism of intentions. Balcanica Posnaniensia. Acta et studia, [S. l.], v. 18, p. 55–66, 2011. DOI: 10.14746/bp.2011.18.6. Disponível em: https://pressto.amu.edu.pl/index.php/bp/article/view/54643. Acesso em: 5 aug. 2026.