| Reference number | Title | Date |
| EC/1905/06 | Forster, Sir Martin Onslow: certificate of election to the Royal Society | |
| NLB/32/62 | Copy letter from Robert William Frederick Harrison, to Messrs Harrison & Sons | [20 December 1905] |
| NLB/35/310 | Copy letter from Robert William Frederick Harrison, to Messrs Harrison & Sons | 14 May 1907 |
| NLB/37/690 | Copy letter from Robert William Frederick Harrison to Dr M [Martin] O [Onslow] Foster, Fellow of the Royal Society | 1 May 1908 |
| NLB/62/923 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 8 June 1922 |
| NLB/51/599 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society to Dr Martin Onslow Foster FRS | 4 May 1915 |
| NLB/52/527 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Dr. Martin Onslow Forster, FRS | 7 January 1916 |
| NLB/56/72 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 14 November 1918 |
| NLB/58/213 | Copy letter from Edwin Deller, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 27 March 1920 |
| NLB/58/217 | Copy letter from Edwin Deller, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 29 March 1920 |
| NLB/55/253 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 05 February 1918 |
| NLB/59/615 | Copy letter from Edwin Deller, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 23 October 1920 |
| NLB/59/430 | Copy letter from Edwin Deller, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS; Salters' Institute of Industrial Chemistry, Salters' Hall, E.C.4. | 2 October 1920 |
| NLB/57/167 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Dr MO [Martin Onslow] Forster, FRS | 1 August 1919 |
| NLB/55/655 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 11 July 1918 |
| NLB/62/75 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 25 November 1921 |
| NLB/62/800 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Dr. [Martin Onslow] Forster, FRS | 9 May 1922 |
| NLB/70/409 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Dr [Martin Onslow] Forster, FRS | 25 March 1927 |
| NLB/72/437 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Dr [Martin Onslow] Forster, FRS | 22 October 1929 |
| IM/001500 | Forster, Martin Onslow | 1924 |
| NLB/56/398 | Copy letter from Dr. Arthur Schuster, Secretary of the Royal Society; to Professor [Percy Faraday] Frankland, FRS | 29 January 1919 |
| NLB/57 | New Letter Book volume 57, copy letters sent from Royal Society administration | 27 June 1919-27 February 1920 |