Letter, 5 April 1889
Letter, 23 April 1889
Letter, 25 May 1899
Letter, 2 June 1899
Letter, 15 June 1899
Letter, 6 July 1899
Letter, 17 January 1899
Letter, 17 January 1899
Letter, 28 March 1899
Letter, 28 March 1899
Notes, Paper of 1889 subsequent work
Letter, 21 June 1899