Y geiriadur mawr =
Subtitle: The complete Welsh-English, English-Welsh dictionary
By: (gan) H.Meurig Evans, W.O. Thomas; golygdd ymgyngh-orol (consulting editor) Stephen J. Williams.
Contributors: Thomas, W. O.; Williams, Stephen J. 1896-
Edition: New ed.
Publisher: Llyfrau'r Dryw; Gwasg Aberystwyth
Published: 1960
Place of publication: Llandybie; Aberystwyth
Language: eng
Notes: First edition 1958.