"A Sand County Almanac: And Sketches Here and There". Book by Aldo Leopold. Chapter "Arizona and New Mexico: Thinking Like a Mountain", p. 130-132, 1949.
Aldo Leopold (2013). “Aldo Leopold: A Sand County Almanac & Other Writings on Conservation and Ecology: (Library of America #238)”, p.473, Library of America
Aldo Leopold (2013). “Aldo Leopold: A Sand County Almanac & Other Writings on Conservation and Ecology: (Library of America #238)”, p.556, Library of America