Columbia subject headings:
Concord River (Mass.)--Description and travel.
Merrimack River (N.H. and Mass.)--Description and travel.
Thoreau, Henry David, 1817-1862.
Harvard subject headings:
Concord River (Mass.)--Description and travel.
Concord River Valley (Mass.)--Description and travel.
Merrimack River (N.H. and Mass.)--Description and travel.
Merrimack River Valley (N.H. and Mass.)--Description and travel.
Thoreau, Henry David, 1817-1862--Travel--Massachusetts--Concord River.
Thoreau, Henry David, 1817-1862--Travel--Merrimack River (N.H. and Mass.)
Princeton subject headings:
Concord River (Mass.)--Description and travel.
Concord River Valley (Mass.)--Description and travel.
Merrimack River (N.H. and Mass.)--Description and travel.
Merrimack River Valley (N.H. and Mass.)--Description and travel.
Thoreau, Henry David, 1817-1862--Travel--Massachusetts--Concord River.
Thoreau, Henry David, 1817-1862--Travel--Merrimack River (N.H. and Mass.).