Using Faceted Search
The search tool on the CIA FOIA Electronic Reading Room is a keyword search that is comprehensive of all declassified documents on the site, as well as all pages on the site, and allows the user to progressively filter their search results by clicking on various search 'facets'. For example, a search for the term 'Russia' will return all records that match this keyword. To the right of the search results are lists of all collections that have documents that match the term, and clicking one of these links will filter the search results by that collection. There are also filters available for the document type, and clicking on one of these links will further filter the results.
If you are on a collection page, then the search will be pre-filtered by that collection.