SIMPSON, J Y. On the sculpturings of cups and concentric rings observed on stones and rocks in various parts of Scotland &c. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 5, p. 299–303, 1865. DOI: 10.9750/PSAS.005.299.303. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/5136. Acesso em: 25 apr. 2024.