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1. Olympic (HTML: 1954) (PDF: 1954, 1957, 1961)	1. Olympic (HTML: 1965) (PDF: 1965)	2. Badlands (HTML: 1962) (PDF: 1954, 1962)
3. Rocky Mountain (HTML: 1954) (PDF: 1954)	3. Rocky Mountain (PDF: 1963)	4. Saguaro (HTML: 1957) (PDF: 1957)
5. Great Smoky Mountains (HTML: 1961) (PDF: 1960, 1961)	6. Organ Pipe Cactus (HTML: 1964) (PDF: 1964)

Saguaro (HTML: 1972) (PDF: 1972)	Saguaro (PDF: 1985)
Everglades Wildguide (HTML: 1972) (PDF: 1972)	Historical Handbook #143 Everglades wildguide : the natural history of Everglades National Park, Florida (1988)
"The place where Hell bubbled up": A History of the First National Park (1972) (HTML edition)	Yellowstone Wildlife (1972)	Many-storied Mountains: The Life of Glacier National Park (1972) (HTML edition)
The life of lava beds (1973)	The Life of Isle Royale (1975) (HTML edition)	The Nature of Shenandoah: A Naturalist's Story of a Mountain Park (1975) (HTML edition)
Mountains and Meadowlands Along the Blue Ridge Parkway (1975)	Cumberland Island : a place apart (1977)	Stehekin: A Wilderness Journey into the North Cascades (1977)
Craters of the Moon: Life in a Volcanic Landscape (1978)	Discovering Delaware Water Gap (1978) (HTML edition)	Discovering Fire Island: The Young Naturalist's Guide to the World of the Barrier Beach (1978)

1. Eastern Deciduous Forest: Volume 1 — Southeastern Evergreen and Oak-Pine Region (1975)

2. Inland Wetlands of the United States (1975)

3. Eastern Deciduous Forest: Volume 2 — Beech-Maple Region (1976)

Geological History of Crater Lake (1912)	Some Lakes of Glacier National Park (1912)	Analyses of the Waters of The Hot Springs of Arkansas Geological Sketch of Hot Springs, Arkansas (1912)
Geological History of the Yellowstone National Park (1912)	Sketch of Yosemite National Park and an Account of the Origin of the Yosemite and Hetch Hetchy Valleys (1912)	The Glacier National Park: A Popular Guide to Its Geology and Scenery (1914) (HTML edition)
Glaciers of Glacier National Park (1914)	Forests of Crater Lake National Park (1916)	The Geologic Story of the Rocky Mountain National Park, Colorado (1917) (HTML edition)
Wild Animals of Glacier National Park (1918)	Mountaineering in the Rocky Mountain National Park (1919)	Early History of Yosemite Valley, California (1919)
Forests of Yosemite, Sequoia, and General Grant National Parks (1920)	Origin of the Scenic Features of the Glacier National Park (1921)	Fishes of the Yellowstone National Park (1921)
Fossil Forests of the Yellowstone National Park (1921)	Geysers of the Yellowstone National Park (1921, 1929)	The Secret of the Big Trees—Yosemite, Sequoia and General Grant National Parks (1921)
Features of the Flora of Mount Rainier National Park (1922)	The Forests of Mount Rainier National Park (1922)	Plants of Glacier National Park (1926)
Mammals and Birds of Mount Rainier National Park (1927)	Mount Rainier and Its Glaciers (1928)	Geological History of the Yellowstone National Park (1928)
Plants of Rocky Mountain National Park (1933)	Plants of Yellowstone National Park (1936)	Among the Birds in the Grand Canyon Country (1939)
Fishes of Glacier National Park, Montana (1941)	A Guide to the Geology of Rocky Mounain National Park, Colorado (1944)	Flora of Mount Rainier National Park (1947, 1956 rev. ed.)
Dinosaur National Monument: Past and Present (1949)	Plants of Big Bend National Park (1951, 1957 reprint)	Plants of Rocky Mountain National Park (1953 rev. ed.)
Forests and Trees of the National Park System (1954)	A Guide to the Geology of Rocky Mounain National Park, Colorado (1955) (HTML edition)	The Dinosaur Quarry (1958) (HTML edition)
The Dinosaur Quarry (1958, reprint 1961)	The Giant Sequoias of California (1942)	The Giant Sequoias of California (1961)