1. The Security Puzzle: Theory-Building and Discipline-Building in International Security;Helga Haftendorn;Ambiguous both in content and format,1991
2. National Security & Civil Liberties;I;The Yale Journal of World Public Order,1982
3. (a concept which is "difficult to give a comprehensive definition"), Schultze also noted that "The concept of national security does not lend itself to a neat and precise formulation;Others V Cg;Foreign Affairs,1972