(A)neirin/Aneurin of the Votadini. Y Guotoðin (The Gododdin: The Votadini), in Llyfr Aneirin/Aneurin (Book of Aneirin/Aneurin). Sixth/Seventh/Ninth/Tenth Centuries AD (c AD 600):

ab Ithel, John Williams, tr. Y Gododin: A Poem on the Battle of Cattraeth by Aneurin, A Welsh Bard of the Sixth Century. Llandovery (London): William Rees (Longman, and Co), 1852.
https://ia801706.us.archive.org/15/items/ygododinpoemonba00anei/ygododinpoemonba00anei.pdf

Clancy, Joseph P. The Gododdin: Book of Aneurin I. London & New York: Macmillan, 1970.
http://www.maryjones.us/ctexts/a01b.html

Skene, William Forbes. The Four Ancient Books of Wales. Edinburgh: Edmonston and Douglas, 1868.
   “The Gododdin: Book of Aneurin I”.
      http://www.maryjones.us/ctexts/a01a.html
   “Y Gododdin”.
      http://www.maryjones.us/ctexts/a01w.html