1. Twain, Mark . Letter to Mollie P. Fairbanks. Aug. 6, 1877. MS. Henry E. Huntington Library, San Marino, CA. Mark Twain’s Letters, 1853–1880. Mark Twain Project Online. www.marktwainproject.org.
2. Goodman, Joseph . Letter to Samuel Clemens. Jan. 29, 1882. MS. Mark Twain Papers. Bancroft Library, University of California, Berkeley.