Calder, Charles S T, and A J H Edwards. “Excavations of Three Neolithic Chambered Cairns – One With an Upper and a Lower Chamber – in the Islands of Eday and the Calf of Eday in Orkney: Including Report on the Pottery”. Proceedings of the Society of Antiquaries of Scotland, vol. 72, Nov. 1938, pp. 193-1, doi:10.9750/PSAS.072.193.213.