Columbia subject headings:
National parks and reserves--Fees--United States.
Public lands--Recreational use--United States--Costs.
Recreation areas--United States--Finance.
United States. National Park Service.
User charges--United States.
Harvard subject headings:
National parks and reserves--Fees--United States
Public lands--Recreational use--United States--Costs.
Recreation areas--United States--Finance.
United States. National Park Service
User charges--United States.
Princeton subject headings: