John Muir (2015). “John Muir’s Incredible Travel Memoirs: A Thousand-Mile Walk to the Gulf, My First Summer in the Sierra, The Mountains of California, Travels in Alaska, Steep Trails… (Illustrated): Adventure Memoirs & Wilderness Studies from the Naturalist, Environmental Philosopher and Early Advocate of Preservation of Wilderness, the Author of The Yosemite and Picturesque California”, p.136, e-artnow
John Muir (1997). “Nature Writings: The Story of My Boyhood and Youth, My First Summer in the Sierra, the Mountains of California, Stickeen, Selected Essays”, p.814, Library of America
John Ruskin “Two paths. Lectures on art, delivered before the University of Oxford in Hilary Term, 1870. Aratra Pentelici. Time and tide. Pre-Raphaelitism. The eagle's nest. King of the Golden River. The relation between Michael Angelo and Tintoret”