The correspondence files contain approximately 7800 letters in original or photocopy, arranged alphabetically within four sub-series: 1) General correspondence A-Z, 1940-1984; 2) Correspondence in response to Paetel's article in Die Zeit, 1947-1948; 3) Correspondence with publishers and re: publications, 1941-1983; and 4) Correspondence with organizations, institutions, 1941-1981.