| RefNo | Title | Source |
| WP/16/1/3 | Letter to William Greenell Wallace from the British Association for the Advancement of Science, London, signed O J R Howarth | |
| DF/ZOO/206/159 | British Association Galapagos Islands Committee: letters of O J R Howarth, Secretary | |
| WP/16/1/5 | Letter to William Greenell Wallace from the British Association for the Advancement of Science, Down House, Farnborough, Kent, signed O J R Howarth | |
| DF/ZOO/232/6/10/8/9 | Howarth, O.R. | |
| DF/MIN/1/59/35 | British Association | |
| DF/ZOO/232/6/15/2/1 | B A (British Association for the Advancement of Science) | |