ヘンリー・デイヴィッド・ソロー
Walls has researched the intersections of literature and science in the works of Ralph Waldo Emerson, Henry David Thoreau, Alexander von Humboldt and related authors. She specializes in American Transcendentalism—especially Henry David Thoreau and Ralph Waldo Emerson, transatlantic romanticism, literature and science, and environmental literature and ecocriticism.