A look at declassified Project RAND reports from 1951-1956, including balloon reconnaissance of USSR.
A quick look at where to find information on CIA's Cold War era SIGINT activites.
On the Area Handbooks funded by the U.S. Army.
Soviet analysis from the CIA: USSR (Monthly) Reviews from 1982 to 1991.
About the JANIS publications of 1943-1947 in the CIA archive: what they are and where to find them.
Some background on CIA's National Intelligence Daily report, and a collection of links to over 2,700 reports.
National Intelligence Surveys: what are they and where to find them.