The invisible weapons - Silber, Jules Crawford. [from old catalog] (London, Hutchinson & co., limited, 1932)
The story of a German secret service agent who was employed by the British Postal censorship during the war.
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Keywords: World War, 1914-1918 -- Censorship -- Great Britain; World War, 1914-1918 -- Propaganda; World War, 1914-1918 -- Secret service -- Germany