Cloustan, Robert Stewart. “Notice of the Excavation of a Chambered Cairn of the Stone Age, at Unstan, in the Loch of Stennis, Orkney”. Proceedings of the Society of Antiquaries of Scotland 19 (November 30, 1885): 341–351. Accessed May 8, 2024. https://journals.socantscot.org/index.php/psas/article/view/6159.