Heald, A (2001) Knobbed spearbutts of the British and Irish Iron Age: new examples and new thoughts, Antiquity, 75(290), pp. 689–96.

‘The northern distribution has also been strengthened – re-analysis of old collections by the writer has uncovered new doorknob spearbutt moulds from Traprain Law, East Lothian and Dun Mor Vaul, Tiree, while similar moulds were recently discovered at Mine Howe, Orkney. It is now clear that doorknob spearbutts were being widely used in Ireland, Scotland and England. How then are we to interpret these new patterns?’