Tatheus (Tathan, Tatheus)

Further reading
S. Baring-Gould and John Fisher, The Lives of the British Saints (London: Honourable Society of Cymmrodorion, 1913), 211–14 View online
David Farmer, The Oxford Dictionary of Saints (Oxford: Oxford University Press, 2011), 409
Elissa Henken, Traditions of the Welsh Saints (Cambridge: D.S. Brewer, 1987), 106–7, 363–4