PISAREK, Stanisław. Peter Berglar, Petrus. Vom Fischer zum Stellvertreter. Śląskie Studia Historyczno-Teologiczne, [S. l.], v. 1992, p. 406–411, 1993. Disponível em: https://journals.us.edu.pl/index.php/ssht/article/view/21437. Acesso em: 5 luty. 2026.