Henry David Thoreau, Barry Andrews (2005). “True Harvest: Readings from Henry David Thoreau for Every Day of the Year”, p.107, Unitarian Universalist Association of Congregations
"Answers to Correspondents". Essay by Mark Twain, first published in The Californian (June 17, 1865), reprinted in Mark Twain's book "The Celebrated Jumping Frog of Calaveras County, and Other Sketches", 1867.