Egni'r ddaear /
McSharry, Gabrielle.
Roberts, Glenys Mair.
Welsh Joint Education Committee.Cynllun Adnoddau.
Araul.
Caerdydd : Qualitex mewn cydweithrediad â Longman Group,
1994.
Arg. Saesneg gwreiddiol o = Original English ed: Harlow: Longman Group, 1992
Testun tu mewn i'r cloriau = Text on inside covers
Teitl clawr = Cover title
Cyhoeddwyd dan nawdd Cynllun Adnoddau Cyd-bwyllgor Addysg Cymru = Published under the auspices of the Welsh Joint Education Committee Resource Project
Power resources