Du Chaillu, P. B., The Viking Age, 2 vols., London, 1889; Earl of Ellesmore, Guide to Northern Archaeology, London, 1848; Duczko, W., The Filigree and Granulation Work of the Viking Period, Stockholm, 1985; Boe, J. Viking Antiquities in Great Britain and Ireland, part III, Norse Antiquities in Ireland, Oslo, 1940; and twenty others of similar interest (25)