From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
File note regarding the bonnet for B.III and B.50 models.
| Identifier | ExFiles\Box 98\3\ scan0142 | |
| Date | 2nd December 1938 | |
| 405 Rm.{William Robotham - Chief Engineer} By/Ald{F. Allwood - Experimental Design}-2/G 2.12.38 B.III, B.50 Bonnet file 405 | ||