1. Before Bletchley Park : the codebreakers of the First World War /: the codebreakers of the First World War. (2020) Authors: Gannon, Paul Record Type: Book Extent: 1 online resource, illustrations (black and white) View Content: Available online (eLD content is only available in our Reading Rooms) ↗
2. SIGINT : the secret history of signals intelligence 1914-45 /: the secret history of signals intelligence 1914-45. (2013) Authors: Matthews, Peter, 1929- Record Type: Book Extent: 1 online resource (160 pages) View Content: Available online (eLD content is only available in our Reading Rooms) ↗