Edwards, A.J.H. 1925. Excavation of a Chambered Cairn at Ham, Caithness, and of a Hut-Circle and Two Earth-Houses at Freswick Links, Caithness: With a Note on a Winged Horse carved on one of the Lintels in the Earth-House at Crichton Mains, Midlothian. Proceedings of the Society of Antiquaries of Scotland. 59, (Nov. 1925), 85–95. DOI:https://doi.org/10.9750/PSAS.059.85.95.