Sources: NNAF
- SLC to Helen Keller, 17 March 1903 · Riverdale, N.Y · UCCL06599 NNAF
- SLC to Helen Keller, 26 July 1904 · Lee, Mass · UCCL06904 NNAF
- Jean Clemens for SLC to Anne S. Macy, 19 January 1905 · New York, N.Y · UCCL10678 NNAF
- SLC to Helen Keller, 6 December 1905 · New York, N.Y · UCCL10680 NNAF
- SLC to Helen Keller, 23 December 1906 · New York, N.Y · UCCL07595 NNAF
- SLC to Helen Keller, 14 November 1908 · Redding, Conn · UCCL10684 NNAF
- SLC per Isabel V. Lyon to Helen Keller, 22 November 1908 · Redding, Conn · UCCL10683 NNAF
- SLC to Helen Keller, 8 January 1909 · Redding, Conn · UCCL10681 NNAF
- SLC to Anne S. Macy, 8 January 1909 · Redding, Conn · UCCL10682 NNAF
- SLC to Anne S. Macy, 11 January 1909 · Redding, Conn · UCCL09387 NNAF
- SLC to John A. Macy, 25 February 1909 · Redding, Conn · UCCL10685 NNAF
- SLC to John A. Macy, 27 March 1909 · Redding, Conn · UCCL10686 NNAF, CU-MARK
- SLC to John A. Macy, 8 April 1909 · Redding, Conn · UCCL10687 NNAF
- SLC to Helen Keller, 29 June 1909 · Redding, Conn · UCCL08429 NNAF
- SLC to Helen Keller, 26 December–26 January 1910 · Hamilton, Bermuda · UCCL10688 NNAF
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