Omar Khayyam, Edward FitzGerald, Christopher Decker (1997). “Edward FitzGerald, Rubáiyát of Omar Khayyám: A Critical Edition”, p.122, University of Virginia Press
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