Gwyddoniaeth trwy brofiad.
Campbell, Les.
Llandysul : Gomer mewn cydweithrediad â Heinemann Educational Books,
1991.
Arg Saesneg gwreiddiol = Original English ed: London: London Inner Education Authority, 1988
Cyfieithydd = Translator: Elfrys Jones
Rhai manylion teitl o'r clawr = Some title information from cover
Developmental biology
Science