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).
Diagram showing the dimensions and specifications for a 20 x 55 cell core.
| Identifier | ExFiles\Box 149a\3\ scan0165 | |
| Date | 9th September 1936 guessed | |
| 20 x 55 CELL CORE .55" .20" AIR GAP .040" BETWEEN LOUVERS EUGENE DIETZGEN CO. NO. 340-10 EDCO EFFICIENCY 10 X 10 PER INCH PRINTED IN U.S.A. F.A.2.A | ||