"The Reader of Gentlemen's Mail: Herbert O. Yardley and the Birth of American Codebreaking".
ISBN 0300098464 , Yale University Press, March 2004
Amazon's page has a couple of good detailed reviews http://www.amazon.com/exec/obidos/ASIN/0300098464/qid=1105254301/sr=2-1/ref=pd_ka_b_2_1/102-1630364-0272149
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Bill Stewart [EMAIL PROTECTED]
