Johnston, A.W. 1903. Notes on the Earl’s Bú (or Bordland) at Orphir, Orkney, called Örfjara in the Sagas, and on the Remains of the round church there. Proceedings of the Society of Antiquaries of Scotland. 37, (Nov. 1903), 16–31. DOI:https://doi.org/10.9750/PSAS.037.16.31.