Allen, John Romilly. “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”. Proceedings of the Society of Antiquaries of Scotland, vol. 25, Nov. 1891, pp. 422-31, doi:10.9750/PSAS.025.422.431.