Sources: CtHi
- Samuel L. Clemens to Joseph R. Hawley, 14 February 1869 · Ravenna, Ohio · UCCL00253
- SLC to Morgan G. Bulkeley, 5 January 1876, Hartford, Conn · UCCL13591
- Samuel L. Clemens to James Hammond Trumbull, 20? June 1876 · Elmira, N.Y · UCCL05077
- SLC to Morgan G. Bulkeley, 11 October 1876 · Hartford, Conn · UCCL13593
- Samuel L. Clemens to Rose Terry Cooke, 17 December 1880 · Hartford, Conn · UCCL01875
- SLC to James Hammond Trumbull, 1 February 1881 · Hartford, Conn · UCCL01902
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