Sources: NRU
- Samuel L. Clemens to Adam Badeau, 4 July 1873 · London, England · UCCL00942
- SLC to Sigmund Schlesinger, 20 May 1898 · Vienna, Austria · UCCL00228
- SLC to Sigmund Schlesinger, 28 July 1898 · Kaltenleugeben, Austria · UCCL00295
- SLC to Isabel V. Lyon and Jean Clemens, 18 October 1904 · New York, N.Y · UCCL06931
- SLC to Harper & Brothers, 1904 · Unknown place · UCCL06925
- SLC to Louis Wiley, 30 December n.y. · Unknown place · UCCL02823
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