LEWIS, John. Excavations at Balvaird Castle, Perthshire. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 122, p. 365–382, 1993. DOI: 10.9750/PSAS.122.365.382. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/9446. Acesso em: 19 apr. 2024.