Treaties and other international acts series. 3610. Technical cooperation, water resources and well drilling programs, agreement between United States and Ethiopia amending and extending agreement of June 23 and 24, 1952, as amended and extended, effected by exchange of notes dated Addis Ababa June 26 and 27, 1956; [entered into force June 27, 1956, operative retroactively May 11, 1956].