Includes indexes. "Declassified and approved for release by NSA on 07-13-2015 pursuant to E.O. 13526." "13 April 1948"--Volume 1; "15 January 1947"--Volume 2. "DGAS-13"--Volume 1; "DGAS-13"--Volume 2. "Prepared under the Direction of the Chief, Army Security Agency, CSGAS-13."