Gordon, G., and A. Mitchell. “Notice of Incised Sculpturings on the Steatite Rock at Feideland, the Extreme North of the Mainland of Shetland, and of a Cluster of Ruined Structures Styled Picts’ Houses, on the Kaim of Isbister, Shetland.”. Proceedings of the Society of Antiquaries of Scotland, Vol. 12, Nov. 1877, pp. 202-6, doi:10.9750/PSAS.012.202.206.