Richard Parsons. (2003). "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd.
Lua i Stíl Chicago (17ú heag.)Richard Parsons. "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd, 2003.
Lua MLA (9ú heag.)Richard Parsons. "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd, 2003.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.