Correspondence, manuscripts, a document, subject files and printed materials of Sack. The collection chiefly concerns American claims against Soviet Russia, and the currency of Estonia and other successor states. The collection contains a 1928 document signed by George F. Kennan. The manuscripts include essays and memoranda concerning currency exchange, tax laws and a number of American court cases involving financial affairs immediately after the 1917 revolution. There are subject files relating to diplomatic claims concerning debts, and the Soviet-Estonian peace conference of 1920. Among the printed materials are clippings and various American statutes and laws.