Gwyddoniaeth : cyfnod allweddol dau : y llyfr gwaith /
Parsons, Richard.
Hughes, Carroll.
University of Wales, Aberystwyth.Centre for Educational Studies.
Aberystwyth : Y Ganolfan Astudiaethau Addysg,
2001.
Addasiad Cymraeg gan = Welsh Adaptation by : Carroll Hughes.
Argraffiad Saesneg gwreiddiol = Original English edition : Kirkby-in-Furness : Coordination Group Publications, 2001.
Science