Sources: CtHT-W
- William D. Howells to SLC, 30 December 1885 · Auburndale, Mass. · UCLC42833 CtHT-W
- SLC to Charles H. Clark, 3 January 1886 · Hartford, Conn · UCCL03352 CtHT-W
- William D. Howells to SLC, 13 May 1887 · Auburndale, Mass. · UCLC43295 CtHT-W
- SLC to Charles H. Clark, 13 August 1887 · Elmira, N.Y · UCCL03625 CtHT-W
- SLC to Joseph H. Twichell, 2 December 1898 · Vienna, Austria · UCCL05473 CtHT-W
- SLC to Joseph H. Twichell, 4 March 1900 · London, England · UCCL05769 CtHT-W
- SLC to Joseph H. Twichell, 23 April 1905 · New York, N.Y · UCCL07033 CtHT-W
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