JAKOBSEN, Erik Maagaard. Fribrødre Å: Geologi i vikingetid. Varv, [S. l.], v. 1987, n. 4, p. 104–115, 1987. DOI: 10.7146/varv.v1987i4.152132. Disponível em: https://tidsskrift.dk/varv/article/view/152132. Acesso em: 6 dec. 2025.