Smith, J.A. 1876. Notes of oblong and horse-shoe shaped flint implements and Arrow-heads found in Kincardineshire. Also Note of the Use of a Stone as a Knife, in the Island of Lewis in 1829. Proceedings of the Society of Antiquaries of Scotland. 11, (Nov. 1876), 575–580. DOI:https://doi.org/10.9750/PSAS.011.575.580.