Anderson, J. 1871. Notes on the Evidence of Spinning and Weaving in the Brochs or Pictish Towers supplied by the Stone Whorls and the Long-handled ’Broch Combs’ found in them. Proceedings of the Society of Antiquaries of Scotland. 9, (Nov. 1871), 548–561. DOI:https://doi.org/10.9750/PSAS.009.548.561.