Environmental Protection

The Incredible Travel Tales of John Muir (Illustrated Edition)

The Mountains of California (With Original Drawings & Photographs)

The Impossible Five

The Sustainable Living Guide

Sister Nature

Swimming Upstream

Climate Change Is Racist

The Trail of the Sandhill Stag

The Barren Ground Caribou of Keewatin

Whale Primer, with Special Attention to the California Gray Whale

The Underworld of Oregon Caves National Monument

Take a Can of Salmon

The Geology of D.A.R. State Park, Mt. Philo State Forest Park, Sand Bar State Park

The Geology of Button Bay State Park

Birds of the National Parks in Hawaii

Secrets of Earth and Sea

Fossil Forests of the Yellowstone National Park

Our Wild World

Titan of Chasms: The Grand Canyon of Arizona

Atoms, Nature, and Man: Man-made Radioactivity in the Environment