Não informado. Outdoor Recreation Research. U.S. Department of the Interior, Bureau of Outdoor Recreation.
Čikaški stil citiranja (17. izdanje)Não informado. Outdoor Recreation Research. Washington: U.S. Department of the Interior, Bureau of Outdoor Recreation.
MLA način citiranja (8. izdanje)Não informado. Outdoor Recreation Research. U.S. Department of the Interior, Bureau of Outdoor Recreation.
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