Sources: MoHH
- Samuel L. Clemens to the Staff of Roberts Opera House, 23 February 1874 · Hartford, Conn · UCCL11957 CSunval2, MoHH
- Samuel L. Clemens to James W. McDaniel, 5 November 1879 · Hartford, Conn · UCCL11805 MoHH
- SLC to Chatto & Windus, 21 October 1892 · Florence, Italy · UCCL12936 MoHH
- SLC to Unidentified, 7 July 1900 · London, England · UCCL12553 MoHH
- SLC to William W. Ellsworth, 31 January 1902 · Riverdale, N.Y · UCCL12007 CSunval2, MoHH
- SLC to Edward Quintard, 1 December 1908 · Redding, Conn · UCCL12390 MoHH
- SLC to Mrs. Edward Quintard, 1 October 1909 · Redding, Conn · UCCL12426 MoHH
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