Anderson, J. 1872. Notice of the Excavation of the Brochs of Yarhouse, Brounaben, Old Stirkoke, Bowermadden, and Dunbeath, in Caithness; with Remarks on the Period of the Brochs; and an Appendix, containing a List of Brochs in Scotland, and Early Notices of many of them. Proceedings of the Society of Antiquaries of Scotland. 9, (Nov. 1872), 292. DOI:https://doi.org/10.9750/PSAS.009.292.