Sources: IU-R
- Samuel L. Clemens to Benjamin P. Shillaber, 28 May 1870 · Buffalo, N.Y · UCCL00470
- Samuel L. Clemens to Unidentified, 6 January 1871 · Buffalo, N.Y · UCCL11886
- Samuel L. Clemens to George Bentley per Fanny C. Hesse, 5 December 1876 · Hartford, Conn · UCCL12341
- Samuel L. Clemens to George Bentley, per Fanny C. Hesse, 12 February 1877 · Hartford, Conn · UCCL12342
- Samuel L. Clemens to George Bentley, 3 August 1877 · Elmira, N.Y · UCCL12343
- Samuel L. Clemens to Chatto and Windus, 1 December 1880 · Hartford, Conn · UCCL01863
- SLC to James R. Osgood, 3 June 1881 · Hartford, Conn · UCCL01968
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