Letter, 30 July 1841
Letter, 22 July 1870
Letter, 23 November 1899
Letter, 19 May 1841
Letter, 27 July 1870
Letter, 27 July 1870
Letter, 17 May 1841
Meeting minutes, Geological Society, Burlington, 23 November 1899
Letter, 29 July 1870
Letter, 23 November 1899