Gwefr gwyddoniaeth.
Johnson, Keith,1938-
Adamson, Sue.
Williams, Ceri.
Williams, Gareth.
University College of Wales.Centre for Educational Studies.
Aberystwyth : Y Ganolfan Astudiaethau Addysg,
c1999.
Arg.Saesneg gwreiddiol = Original English ed.: Cheltenham: Stanley Thornes, 1995.
Addasiad Cymraeg gan = Welsh adaptation by: Ceri Williams, John Williams, Sandra Williams a Delyth Ifan.
Yn cynnwys mynegai = Includes index.
Science