Heacox, K. (2016). National Geographic the national parks: An illustrated history. National Geographic.
Chicago-viite (17. p.)Heacox, Kim. National Geographic the National Parks: An Illustrated History. Washington, D.C: National Geographic, 2016.
MLA-viite (9. p.)Heacox, Kim. National Geographic the National Parks: An Illustrated History. National Geographic, 2016.
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