Calder, Charles S T. “A Neolithic Double-Chambered Cairn of the Stalled Type and Later Structures on the Calf of Eday, Orkney”. Proceedings of the Society of Antiquaries of Scotland 71 (November 30, 1937): 115–154. Accessed November 22, 2024. https://journals.socantscot.org/index.php/psas/article/view/8042.