Ritchie, James. “Cup-Marks on the Stone Circles and Standing-Stones of Aberdeenshire and Part of Banffshire”. Proceedings of the Society of Antiquaries of Scotland 52 (November 30, 1918): 86–121. Accessed April 19, 2024. https://journals.socantscot.org/index.php/psas/article/view/7444.