Richard Parsons. (2003). "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd.
Cita Chicago Style (17a ed.)Richard Parsons. "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd, 2003.
Cita MLA (9a ed.)Richard Parsons. "National Curriculum Science: Earth, Sun and Moon: Unit 5e (National Curriculum Science)". Coordination Group Publications Ltd, 2003.
Precaución: Estas citas no son 100% exactas.