Sources: DNA
- Samuel L. Clemens to Mortimer D. Leggett with an affidavit by John Hooker, 6 October 1871 · Hartford, Conn · UCCL00656 DNA
- Samuel L. Clemens to Rutherford B. Hayes, 20 September 1877 · Hartford, Conn · UCCL01483 DNA, CU-MARK
- Samuel L. Clemens to John Sherman, 20 September 1877 · Hartford, Conn · UCCL01484 DNA
- Rutherford B. Hayes per Telegraph Operator to Samuel L. Clemens, 20 September 1877 · UCLC32566 DNA
- Samuel L. Clemens to John Sherman, 22 September 1877 · Hartford, Conn · UCCL01487 DNA
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