Charles-Edwards, Gifford. 2005. “A Reconsideration of the Origins of Early Insular Monumental Lettering of the Mixed Alphabet Type: The Case of the ’Lapis Echodi’ Inscription on Iona”. Proceedings of the Society of Antiquaries of Scotland 134 (November):173-81. https://doi.org/10.9750/PSAS.134.173.181.