KIRKNESS, William. A Pillared Underground Chamber at Biggings, Harray, Orkney. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 64, p. 222–232, 1930. DOI: 10.9750/PSAS.064.222.232. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/7791. Acesso em: 26 apr. 2024.