Annandale, T.N. 1898. Notice of Two Hammer-stones (Barkstein) used in the Preparation of Dye from Tormentilla in the Faroe Isles, and of a Faroe Bismar. (Specimens exhibited). Proceedings of the Society of Antiquaries of Scotland. 32, (Nov. 1898), 52–54. DOI:https://doi.org/10.9750/PSAS.032.52.54.