Environmental Protection

Trees of Indiana First Revised Edition (Publication No. 13, Department of Conservation, State of Indiana)

A Gamekeeper's Note-book

The Book of Nature

The Underworld of Oregon Caves National Monument

Island Trail at Walnut Canyon. Walnut Canyon National Monument

The Spell of the White Sturgeon

The Boy With the U. S. Foresters

El Morro Trails: El Morro National Monument, New Mexico

Carlsbad Caverns National Park, New Mexico

Integrated Environmental Footprint Index (IPAI)

Runaway Planet

Wanderings in South America

Fresh Fields

The Spell of the Rockies

The Amateur Poacher

Underground Treasures: How and Where to Find Them

Burton Island State Park: Guide to the Interpretive Nature Trail and Hiking Trail

The Geology of Groton State Forest

The Migration of North American Birds

Krag and Johnny Bear