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).
Reference note regarding production tests of 20/25 electrical components.
| Identifier | ExFiles\Box 60\2\ Scan001 | |
| Date | 1st January 1931 | |
| 1.1.31. X.6087. For previous matter relating to Production tests of 20/25 electrical components see X.5781. | ||