LAING, Samuel. On the Age of the Burgs or ’Brochs,’ and some other Pre-historic Remains, of Orkney and Caithness. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 7, p. 56–100, 1869. DOI: 10.9750/PSAS.007.56.100. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/5313. Acesso em: 2 may. 2024.