Walker Sally M. (2010). Early Bird Earth Science Fossils. Lerner.
Cita Chicago (17th ed.)Walker Sally M. Early Bird Earth Science Fossils. Lerner, 2010.
Cita MLA (9th ed.)Walker Sally M. Early Bird Earth Science Fossils. Lerner, 2010.
Atenció: Aquestes cites poden no estar 100% correctes.