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).
Cross-reference note for the 40/50 switchbox (general).
| Identifier | ExFiles\Box 61b\3\ scan0312 | |
| Date | 1st January 1931 | |
| X.6070. 1.1.31. For previous matter relating to 40/50 switchbox (general) see X.7730. | ||