Thomson, R. L., and Angus Matheson [collector], Foirm na n-urrnuidheadh: John Carswell’s Gaelic translation of the Book of common order, Scottish Gaelic Texts 11, Edinburgh: Oliver and Boyd for the Scottish Gaelic Texts Society, 1970.
Thomson, R. L. [ed.], Pwyll Pendeuic Dyuet: the first of the Four Branches of the Mabinogi, edited from the White Book of Rhydderch, with variants from the Red Book of Hergest, Mediaeval and Modern Welsh Series 1, Dublin: DIAS, 1957.
Thomson, R. L., “Owein: Chwedl Iarlles y Ffynion”, in: Bromwich, Rachel, A. O. H. Jarman, and Brynley F. Roberts (eds.), The Arthur of the Welsh. The Arthurian legend in medieval Welsh literature, Arthurian Literature in the Middle Ages 1, Cardiff: University of Wales Press, 1991. 159–169.