Reference: Llanstephan MS 120E
The 'book of Jaspar Griffith', containing poetry by Dafydd ap Gwilym, Rhys Fardd, Iolo Goch, Taliesin, Dafydd Llwyd ap Llywelyn ap Gruffudd [Dafydd Llwyd, Mathafarn] and others. Jaspar Griffith at one time had in his care or possession Peniarth MS 1 and Peniarth MS 53, both of which are largely copied in this manuscript. The style of the handwriting resembles certain of Griffith's marginalia in Peniarth 1 and 53 so it is inferred that this manuscript is also in his hand.
A detailed list of the manuscript's contents may be found in J. Gwenogvryn Evans, Report on Manuscripts in the Welsh Language, Vol. II, Part II (London, 1903), pp. 603-609.