![National Security Agency: A Priceless Advantage [Pdf] Primary](https://d15y2dacu3jp90.cloudfront.net/images/attachment_defaults/resource/large/FPO-knovation.png "National Security Agency: A Priceless Advantage [Pdf] Primary")
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National Security Agency: A Priceless Advantage [Pdf]
A report written by the NSA on the U.S. Navy Communications Intelligence and the Battles of Coral Sea, Midway, and the Aleutians in the spring of 1942. Very credible and very complete. (Third edition)
ibiblio
Ibiblio: The Silent War Against the Japanese Navy
Extensive article which chronicles the efforts of U.S. Naval intelligence to read the secret radio messages of the Japanese Navy.