MORRIS, Ronald W B. The petroglyphs at Achnabreck, Argyll. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 103, p. 33–56, 1974. DOI: 10.9750/PSAS.103.33.56. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/8789. Acesso em: 5 may. 2024.