Smith, J. A. (1880). Additional Notes to Notice of the Remains of the Great Auk (Alca impennis, Linn.), found in Caithness; with Notes of its Occurrence, &c., in Scotland, and of its Early History. Proceedings of the Society of Antiquaries of Scotland, 14, 436–444. https://doi.org/10.9750/PSAS.014.436.444