I. Williams · S W · S. Williams
| title | ISBN-13 | year of publication |
|---|---|---|
| Canu Taliesin | 978-0-7083-1646-7 | 2000 |
| Pedeir Keinc y Mabinogi Allan o Lyfr Gwyn Rhydderch | 978-0-7083-1407-4 | 1996 |
| The Beginnings of Welsh Poetry | 978-0-7083-0744-1 | 1980 |
| The Beginnings of Welsh Poetry | 978-0-7083-0035-0 | 1972 |