Sources: JIm
- Samuel L. Clemens to James Redpath, 9 July 1869 · Elmira, N.Y · UCCL00325 JIm, CU-MARK
- Samuel L. Clemens to Unidentified, 4 July 1870 · Elmira, N.Y · UCCL02799 JIm
- Samuel L. Clemens to Adolph H. Sutro, 19 August 1871 · Hartford, Conn · UCCL00647 JIm
- Henry W. Shaw (Josh Billings) to SLC, 25 September 1876 · New York, N.Y. · UCLC32424 JIm
- SLC to Joseph H. Twichell, 15 April 1891 · Hartford, Conn · UCCL11514 JIm
- Annie Neumann Hofer to SLC, 11 February 1893 · Berlin, Germany · UCLC45913 JIm
- SLC to Chatto & Windus, 13–15 February 1893 · Florence, Italy · UCCL04340 JIm
- SLC to Henry H. Rogers, 4 March 1894 · New York, N.Y · UCCL04704 JIm
- SLC to Unidentified, 9 August 1894 · New York, N.Y · UCCL04777 JIm
- SLC per Clara L. Clemens to Bram Stoker, 28 June 1899 · London, England · UCCL05645 JIm
- SLC to Francis H. Skrine, 5 February 1902 · Riverdale, N.Y · UCCL06270 JIm
- SLC to Katharine I. Harrison, 16 January 1903 · Riverdale, N.Y · UCCL06563 JIm
- SLC to Frederick T. Leigh and Frederick A. Duneka, 7 January 1910 · Hamilton, Bermuda · UCCL08536 JIm
- SLC to Mary D. Ely, 20 February n.y. · Hartford, Conn · UCCL03105 JIm
- SLC to Unidentified, Unknown date · Unknown place · UCCL11510 JIm
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