[1] The Town's Armorial Bearings & Royal Status (Caernarfon Online)
wikipedia.org
en.wikipedia.org
See Sir en:Ifor Williams' notes in his edition of Breuddwyd Maxen (Bangor, 1920). The name appears for the first time in the work of en:Nennius. Pre-conquest medieval Welsh poets such as en:Hywel ab Owain Gwynedd sometimes use the name Caer Gystennin.