Hewitt (1990)
De Arbres
- Hewitt, Steve. 1990. 'The progressive in Breton in the light of the English progressive', Ball, Fife, Poppe, Rowland, Celtic Linguistics: Readings in the Brythonic Languages Festschrift for T. Arwyn Watkins, Current Issues in Linguistic Theory 68, Benjamins, 167-188.