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. 385, 1865. DOI: 10.9750/PSAS.005.385. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/5156. Acesso em: 5 may. 2024.