224. 1879 – 1900: 27 letters to Bentley, Bentley Archives, University of Illinois Library, reproduced on microfilm. (Letters 25 – 27 predate letter 1; letter 23 belongs between 2 and 3.)
225. 1890 – 1902: 3 letters, Huntington Library.
226. 1890: 1 letter, Robert Lee Wolff collection, cited in item 278.