Sources: RPB-JH
- SLC to Unidentified, November to 15 December? 1879 · Unknown place · UCCL13217
- SLC to John M. Hay, 28 June 1901 · Saranac Lake, N.Y · UCCL06080
- SLC to Joseph H. Twichell, 18 January 1902 · Riverdale, N.Y · UCCL06249
- SLC to James J. Roche, 11 April 1905 · New York, N.Y · UCCL07031
- SLC to Harper’s Weekly editor, 3 October 1905 · Dublin, N.H · UCCL07160
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