Roderick Impey Murchison (1854). “Siluria the History of the Oldest Known Rocks Containing Organic Remains, with a Brief Sketch of the Distribution of Gold Over the Earth by Roderick Impey Murchison”, p.469
Mark Twain (2017). “MARK TWAIN Ultimate Collection: 370+ Titles in One Volume (Illustrated): The Adventures of Tom Sawyer & Huckleberry Finn, The Prince and the Pauper, The £1,000,000 Bank Note, A Horse’s Tale, Yankee in King Arthur's Court, The Innocents Abroad, Life on the Mississippi…”, p.3737, e-artnow