Art of the Picts: Sculpture and Metalwork in Early Medieval Scotland. Thames and Hudson, 2004. Susan Youngs (ed), "The Work of Angels", Masterpieces of Celtic Metalwork, 6th–9th centuries AD, cat. # 72, 1989, British Museum Press, London, , the catalogue entry text quoted on the BM website (click "more" on linked page) Further reading Harbison, Peter. The golden age of Irish art. London: Thames and Hudson, 1999 Archaeology of Scotland Celtic brooches Medieval European objects in the British Museum Silver-gilt objects