“Report on the Sculptured Stones older than A.D. 1100, with Symbols and Celtic Ornament, in the District of Scotland, North of the River Dee; obtained under the Victoria Jubilee Gift of His Excellency Dr. R. H. Gunning, F.S.A. Scot” (1891) Proceedings of the Society of Antiquaries of Scotland, 25, pp. 422–431. doi:10.9750/PSAS.025.422.431.