Allen, J. R. (1897) “Report on the Photography of the Sculptured Stones earlier than A.D. 1100, in the District of Scotland south of the river Dee; obtained under the Jubilee Gift of His Excellency Dr. R. H. Gunning, LL.D., F.S.A. Scot”, Proceedings of the Society of Antiquaries of Scotland, 31, pp. 147–152. doi: 10.9750/PSAS.031.147.152.