Oceanography, cooperation in studies of the world ocean : agreement between the United States of America and the Union of Soviet Socialist Republics, extending the agreement of June 19, 1973, as amended and extended, effected by exchange of notes, dated at Moscow December 13, 1988 and January 3, 1989, and exchange of notes, dated at Moscow March 13 and 30, 1989, and exchange of notes, dated at Moscow June 9 and July 11, 1989, and exchange of notes, dated at Moscow December 11 and 15, 1989