Scientific correspondence, 1869-1889
Scientific correspondence, 1869-1889
Scientific correspondence, 1890-1892
Scientific correspondence, 1890-1892
Scientific correspondence, 1893-1896
Scientific correspondence, 1893-1896
Letters, no date
Letters, no date
Letter, undated
Letter, undated
Letter, undated
Letter, undated
Letter, undated
Letter, undated