Treaties and other international acts series. 6620. Agricultural commodities, sales under title IV, agreement between United States and Yugoslavia, modifying agreements of Apr. 21, 1962, as amended, Apr. 27, 1964, Mar. 16, 1965, and July 16, 1965, effected by exchange of notes, signed Belgrade Dec. 20, 1968; [entered into force Dec. 20, 1968].