Columbia subject headings:
Big Bend National Park (Tex.)
Wild and scenic rivers--Recreational use--Texas.
Wilderness areas--Texas.
Harvard subject headings:
Big Bend National Park (Tex.)
Wild and scenic rivers--Recreational use--Texas.
Wild and scenic rivers--Texas--Recreational use.
Wilderness areas--Texas
Princeton subject headings:
Big Bend National Park (Tex.)
Wild and scenic rivers--Texas--Recreational use.
Wilderness areas--Texas.