HENDERSON, Isabel M. The Origin Centre of the Pictish Symbol Stones. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 91, p. 44–60, 1960. DOI: 10.9750/PSAS.091.44.60. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/8548. Acesso em: 24 apr. 2024.