RITCHIE, P R. A chambered cairn at Isbister, South Ronaldshay, Orkney. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 92, p. 25–32, 1961. DOI: 10.9750/PSAS.092.25.32. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/8573. Acesso em: 16 apr. 2024.