Bibliography:National Security Agency

General works

 * Kahn, David. (1974) The Codebreakers: The Story of Secret Writing. First serious book on NSA, although its publication reflected some compromises about not printing US-UK history and relationships. 2nd Edition is disappointing; it just appends a chapter on US-UK WWII cryptanalysis, rather than revising all relevant sections in the book. First chapter, "One Day of MAGIC", about communications intelligence on December 7, 1941, is a fantastic suspense story even if one knows how it comes out.
 * Bamford, James. (1983) The Puzzle Palace: Inside the National Security Agency, America's Most Secret Intelligence Organization. Informative, but Bamford obviously wasn't thinking of the National Reconnaissance Office or whatever the Intelligence Support Activity is now called.
 * Bamford, James. (2002) Body of Secrets: Anatomy of the Ultra-Secret National Security Agency

Biographies

 * Clark, Ronald W. The Man who Broke Purple. Biography of William F. Friedman, including his NSA years.

Tutorials about NSA-relevant technologies

 * Friedman, William F. Military Cryptanalysis
 * Sinkov, Abraham. Elementary Cryptanalysis: A Mathematical Approach