GRAHAM, Angus. Some Observations on the Brochs. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 81, p. 48–99, 1949. DOI: 10.9750/PSAS.081.48.99. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/8275. Acesso em: 19 apr. 2024.