{"id":"stein1999courtyard","URL":"https://nsarchive2.gwu.edu/NSAEBB/NSAEBB431/docs/intell_ebb_010.PDF","type":"article-journal","title":"The Puzzle at CIA Headquarters: Cracking the Courtyard Crypto","author":[{"given":"David D.","family":"Stein"}],"issued":{"date-parts":[[1999]]},"year-text":"1999","container-title":"Studies in Intelligence 43(1), CIA","catalog-key":"SRC0D7HSVVA2G5B"}