ISBN 1-84212-477-3* Roberts, Brynley F.. "Geoffrey of Monmouth, "Historia Regnum Britanniae" and "Brut y Brenhinedd"" in "The Arthur of the Welsh: The Arthurian Legend in Medieval Welsh Literature", Cardiff, University of Wales Press, 1991, ISBN 0-7083-1307-8* Curley, Michael.
ISBN 1-84212-477-3* Roberts, Brynley F.. "Geoffrey of Monmouth, "Historia Regnum Britanniae" and "Brut y Brenhinedd"" in "The Arthur of the Welsh: The Arthurian Legend in Medieval Welsh Literature", Cardiff, University of Wales Press, 1991, ISBN 0-7083-1307-8* Curley, Michael.