TRAILL, William. Notice of Excavations at Stenabreck and Howmae, in North Ronaldsay, Orkney. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 19, p. 14–33, 1885. DOI: 10.9750/PSAS.019.14.33. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/6130. Acesso em: 6 may. 2024.