Smith, J. A. (1879). Notice of the Remains of the Great Auk, or Gare-fowl (Alca Impennis, Linn.), found in Caithness; with Notes of its Occurrence in Scotland and of its Early History. Proceedings of the Society of Antiquaries of Scotland, 13, 76–105. https://doi.org/10.9750/PSAS.013.76.105