Sources: InU-Li
- Samuel L. Clemens to Charles Henry Webb, 25 November 1867 · Washington, D.C · UCCL00160
- Samuel L. Clemens to Charles Warren Stoddard, 27 or 28 October 1877 · (1st of 5) · Hartford, Conn · UCCL09289
- Samuel L. Clemens to Unidentified, December 1880 · Hartford, Conn · UCCL10817
- SLC to Stewart L. Woodford, 14 December 1882 · Hartford, Conn · UCCL10835
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