Mary C. Neal, M.D. (2012). “To Heaven and Back: A Doctor's Extraordinary Account of Her Death, Heaven, Angels, and Life Again: A True Story”, p.93, WaterBrook
"'We're the first generation that has had the power to destroy the planet. Ignoring that risk can only be described as reckless'". Interview with Decca Aitkenhead, www.theguardian.com. March 29, 2009.
John Muir (2015). “John Muir: The Story of My Boyhood and Youth & Letters to a Friend (Autobiography With Original Drawings): The Memoirs of the Naturalist, Environmental Philosopher and Early Advocate of Preservation of Wilderness, the Author of The Yosemite, Travels in Alaska, The Mountains of California & Steep Trails”, p.129, e-artnow
Oral history interview with Sevim Fesci in New Haven, Connecticut, for the "Archives of American Art," Smithsonian Institution, www.aaa.si.edu. June 22, 1968.