ARMSTRONG, William Bruce. Notice of an Ancient Door-Knocker, with Armorial Bearings, from Muness Castle, Unst, Shetland. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 15, p. 101–103, 1881. DOI: 10.9750/PSAS.015.101.103. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/5956. Acesso em: 4 may. 2024.