Richard Parsons. (2003). "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd.
Citazione stile Chigago Style (17a edizione)Richard Parsons. "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd, 2003.
Citatione MLA (9a ed.)Richard Parsons. "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd, 2003.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.