Sources: OClWHi
- Samuel L. Clemens to Emily A Severance, 24 December 1867 · Washington, D.C · UCCL02780
- Samuel L. Clemens to Emily A. Severance, 27 October 1869 · Elmira, N.Y · UCCL00364
- Samuel L. Clemens to John M. Hay, 12 January 1873 · Hartford, Conn · UCCL00856
- SLC per James Redpath to Unidentified, 13 May 1885 · Hartford, Conn · UCCL03225
- SLC to Gertrude Van R. Wickham, 6 October 1886 · Hartford, Conn · UCCL03464
- To Solon L. Severance, 2 March 1882 • Hartford, Conn · UCCL13884
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