| RefNo | Title | Date |
| EC/1908/05 | Dixon, Henry Horatio: certificate of election to the Royal Society | |
| MM/16/44 | Letter from F O Bower, Ripon, to HH Dixon | 4 December 1946 |
| MM/16/43 | Letter from F O Bower, Ripon, to HH Dixon | 22 September 1946 |
| MM/16/42 | Letter from F O Bower, Ripon, to HH Dixon | 10 March 1928 |
| IM/001170 | Dixon, Henry Horatio | circa 1949 |
| NLB/10/211 | Copy letter from Herbert Rix, to Francis Darwin, Fellow of the Royal Society | 22 October 1894 |
| NLB/10/389 | Copy letter from Herbert Rix, to Professor Michael Foster | 16 November 1894 |
| NLB/13/818 | Copy letter from Robert William Frederick Harrison, to Professor Sydney Howard Vines, Fellow of the Royal Society | 2 December 1896 |
| RR/22/17 | Referee's report by Henry Horatio Dixon, on a paper 'Transmission of death excitation in plants' by Jagadis Chunder Bose | January 1916 |
| NLB/11/551 | Copy letter from Herbert Rix, to Professor [John] Joly | 21 July 1895 |
| AP/73/3 | Unpublished paper, 'Preliminary communication on a theory of the suction-force of branches' by Sidney Howard Vines | 1896 |
| NLB/20/207 | Copy letter from Robert William Frederick Harrison, to Dr Henry Horatio Dixon, [Fellow of the Royal Society], Botanical Laboratory, Trinity College, Dublin | 23 February 1900 |
| NLB/37/871 | Copy Letter from Robert William Frederick Harrison to W [William] Barlow, Fellow of the Royal Society | 26 May 1908 |
| NLB/42/181 | Copy letter from Robert William Frederick Harrison to Messrs Harrison & Sons | 20 April 1910 |
| NLB/51/135 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society to Professor Henry Horatio Dixon FRS | 16 December 1914 |
| RR/27/15 | Referee's report by Henry Horatio Dixon, on a paper 'On the relation between permeability variation and plant movements' by Basiswar Sen | October 1922 |
| RR/27/7 | Referee's report by Henry Horatio Dixon, on a paper 'Further observations on cell-wall structure as seen in cotton hairs' by William Lawrence Balls | March 1922 |
| RR/28/60 | Referee's report by Henry Horatio Dixon, on a paper 'The determiners of cellulose structure as seen in the cell-wall of cotton hairs' by William Lawrence Balls | [April 1923] |
| RR/17/27 | Referee's report by Francis Darwin, on a paper 'On the transpiration current in plants' by Henry Horatio Dixon | [November 1906] |
| RR/36/39 | Referee's report by Henry Horatio Dixon, on a paper 'Electrical effects accompanying the decomposition of organic compounds. III. Photosynthesis and plant nutrition' by M C Potter | [January 1927] |
| RR/60/5 | Referee's report by Henry Horatio Dixon, on a paper 'The diffusion porometer' by Frederick Gugenheim Gregory and J I Armstrong | May 1936 |
| RR/52/104 | Referee's report by Henry Horatio Dixon, on a paper 'Experiments on phyllotaxis - Part III - Diagonal splits through decussate apices' by Mary Snow and R Snow | October 1934 |
| RR/49/148 | Referee's report by Henry Horatio Dixon, on a paper 'The resistance porometer and its application to the study of stomatal movement' by Frederick Gugenheim Gregory and H L Pearse | [December 1933] |
| NLB/57/164 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor VH [Vernon Herbert] Blackman, FRS, Chairman of the Botany Committee | 31 July 1919 |
| RR/63/83 | Referee's report by Henry Horatio Dixon, on a paper 'The potato virus "X": Its strains and reactions' by Redcliffe Nathan Salaman | February 1938 |
| RR/65/123 | Referee's report by Henry Horatio Dixon, on a paper 'Oxygen produced by isolated chloroplasts' by Robert Hill | January 1939 |
| RR/51/77 | Referee's report by Henry Horatio Dixon, on a paper 'Experiments on Phyllotaxis. II. — The effect of displacing a primordium' by Mary Snow and R Snow | [February 1933] |
| RR/26/148 | Referee's report by Henry Horatio Dixon, on a paper 'Experimental researches on vegetable assimilation and respiration. XIV. —Assimilation by submerged plants dilute solutions of bicarbonates and of acids: an improved bubble-counting technique' by A J Wilmott | [July 1921] |
| RR/12/309 | Letter from Francis Darwin, regarding a paper 'On the ascent of sap' by Henry Horatio Dixon and John Joly | 7 March 1895 |
| RR/44/77 | Referee's report by Henry Horatio Dixon, on a paper 'Experiments on phyllotaxis. I. - The effect of isolating a primordium' by Mary Snow and George Robert Sabine Snow | September 1931 |
| RR/45/2 | Referee's report by Henry Horatio Dixon, on a paper 'Respiration as a factor in the ionic equilibria between plant tissues and external solutions' by George Edward Briggs and A H K Petrie | [April 1931] |
| NLB/57 | New Letter Book volume 57, copy letters sent from Royal Society administration | 27 June 1919-27 February 1920 |
| RR/12/90 | Referee's report by Joseph John Thomson, on a paper 'On the ascent of sap' by Henry Horatio Dixon and John Joly | 20 February 1895 |
| NLB/13/733 | Copy letter from Robert William Frederick Harrison, to Professor Sydney Howard Vines, Fellow of the Royal Society | 12 November 1896 |
| NLB/13/784 | Copy letter from Robert William Frederick Harrison, to Professor Sydney Howard Vines, Fellow of the Royal Society | 25 November 1896 |
| RR/12/310 | Referee's report by Francis Darwin, on a paper 'On the ascent of sap' by Henry Horatio Dixon and John Joly | 24 October 1894 |
| AP/71/1 | Paper, 'On the ascent of sap' by Henry H [Horatio] Dixon and J [John] Joly | 1894 |
| RR/12/89 | Referee's report by Francis Darwin, on a paper 'On the ascent of sap' by Henry Horatio Dixon and John Joly | 27 December 1894 |
| RR/12/308 | Referee's report by George Francis Fitzgerald, on a paper 'On the ascent of sap' by Henry Horatio Dixon and John Joly | 17 November 1894 |
| MC/26/64 | Letter from Henry [Horatio] Dixon, School of Botany, Trinity College, Dublin, to Mr [Robert] Harrison, [Royal Society] | 9 December 1911 |