Measures to Prevent International Terrorism Which Endangers or Takes Innocent Human Lives or Jeopardizes Fundamental Freedoms and Study of the Underlying Causes of Those Forms of Terrorism: Report of the Secretary-General: Convening Under the Auspices of the United Nations, of an International Conference to Define Terrorism and to Differentiate it From the Struggle of Peoples for National Liberation: Report of the Secretary-General, U.N. Doc. A/46/346/Add.1 (1 Oct. 1991)