Columbia subject headings:
Harvard subject headings:
Authors, American--19th century--Biography
Human ecology--United States
Indians of North America.
Muir, John, 1838-1914
Naturalists--United States--Biography
Thoreau, Henry David, 1817-1862
Princeton subject headings:
Authors, American--19th century--Biography.
Human ecology--United States.
Indians of North America.
Muir, John, 1838-1914.
Naturalists--United States--Biography.
Thoreau, Henry David, 1817-1862.