Hays, S. P. (2009). The American people & the national forests: The first century of the U.S. Forest Service. University of Pittsburgh Press.
Lua i Stíl Chicago (17ú heag.)Hays, Samuel P. The American People & the National Forests: The First Century of the U.S. Forest Service. Pittsburgh, Pennsylvania: University of Pittsburgh Press, 2009.
Lua MLA (9ú heag.)Hays, Samuel P. The American People & the National Forests: The First Century of the U.S. Forest Service. University of Pittsburgh Press, 2009.
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