Kathleen Weidner Zoehfeld. (2012). National Geographic Readers: Rocks and Minerals (39197th.). National Geographic Children's Books.
Citazione stile Chigago Style (17a edizione)Kathleen Weidner Zoehfeld. National Geographic Readers: Rocks and Minerals. 39197th. National Geographic Children's Books, 2012.
Citatione MLA (9a ed.)Kathleen Weidner Zoehfeld. National Geographic Readers: Rocks and Minerals. 39197th. National Geographic Children's Books, 2012.
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