Columbia subject headings:
Harvard subject headings:
Elk--Ecology--Yellowstone National Park.
Mammals--Ecology
Mammals--Ecology--Yellowstone National Park.
Wildlife management--Yellowstone National Park.
Yellowstone National Park.
Princeton subject headings:
Elk--Yellowstone National Park--Ecology.
Mammals--Ecology.
Mammals--Yellowstone National Park--Ecology.
Wildlife management--Yellowstone National Park.
Yellowstone National Park.