Sources: MiD
- Samuel L. Clemens to Edward H. Paige, 20? May 1870 · Buffalo, N.Y · UCCL11699
- Samuel L. Clemens to James Redpath, 31 December 1873 · London, England · UCCL01023
- Samuel L. Clemens to Thomas Bailey Aldrich, 20 October 1875 · Hartford, Conn · UCCL01274
- Samuel L. Clemens to George S. Merrill, per Fanny C. Hesse, 8 February 1877 · Hartford, Conn · UCCL04140
- SLC to Edward F. Noyes, 26 February 1881 · Hartford, Conn · UCCL01916
- SLC to Karl Gerhardt and Hattie J. Gerhardt, 7 May 1883 · Hartford, Conn · UCCL02379
- SLC to Karl Gerhardt, 11 September 1884 · Elmira, N.Y · UCCL04135
- SLC to Karl Gerhardt, 28 September 1884 · Hartford, Conn · UCCL01443
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