Columbia subject headings:
Colorado--Description and travel.
Natural history--Outdoor books.
Rocky Mountains.
Harvard subject headings:
Colorado--Description and travel.
Longs Peak (Colo.)--Description and travel.
Natural history--Outdoor books
Natural history--Rocky Mountains
Naturalists--United States--Biography
Pioneers--Rocky Mountains--Biography.
Rocky Mountains--Description and travel.
Rocky Mountains.
Princeton subject headings:
Colorado--Description and travel.
Natural history--Outdoor books.
Rocky Mountains.