Sharples, N. M., Barlow, A., Birkett, D. A., Clarke, A., Clarke, A. S., MacCormick, F., … O'Neil, M. (1985). Excavations at Pierowall Quarry, Westray, Orkney. Proceedings of the Society of Antiquaries of Scotland, 114, 75–125. https://doi.org/10.9750/PSAS.114.75.125