Stuart, John, and Ferdinand Keller. “On Some of the Vitrified Forts of Scotland, With Reference to Descriptions of Similar Remains in Bohemia”. Proceedings of the Society of Antiquaries of Scotland 8 (November 30, 1869): 145–164. Accessed April 26, 2024. https://journals.socantscot.org/index.php/psas/article/view/5411.