[en] The Yellowstone National Park University of Oklahoma Press
[en] [Gutenberg 42112] • The Yellowstone National Park: Historical and Descriptive University of Oklahoma Press
[en] Birds of Prey of the World Golden Guides from St. Martin's Press
[en] The Yellowstone National Park University of Oklahoma Press
[en] [Gutenberg 42112] • The Yellowstone National Park: Historical and Descriptive University of Oklahoma Press
[en] Birds of Prey of the World Golden Guides from St. Martin's Press