Mark Twain, John Sutton Tuckey (1980). “The Devil's Race-track: Mark Twain's Great Dark Writings : the Best from Which was the Dream? and Fables of Man”, p.337, Univ of California Press
Thomas Chalmers (1848). “Discourses on the Christian revelation, viewed in connection with the modern astronomy: To which are added, Discourses illustrative of the connection between theology & general science”, p.328
Thomas Chalmers (1848). “Discourses on the Christian revelation, viewed in connection with the modern astronomy: To which are added, Discourses illustrative of the connection between theology & general science”, p.328