Mackay, Angus. “Notes on a Slab With Incised Crescentic Design, Stone Mould for Casting Spear-Heads, a Cup-Marked Stone, Holy-Water Stoup, and Other Antiquities in Strathnaver, Sutherlandshire”. Proceedings of the Society of Antiquaries of Scotland, vol. 40, Nov. 1906, pp. 128-33, doi:10.9750/PSAS.040.128.133.