1. Alchourrón, C. E., 1993, ?Philosophical Foundations of Deontic Logic and the Logic of Defeasible Conditionals?, in J.J. Meyer and R.J. Wieringa (Ed.): Deontic Logic in Computer Science: Normative System Specification, Wiley & Sons.
2. Alchourrón, C. E., ?Defeasible Logics: Demarcation and Affinities? in G. Crocco, L. Fariñas del Cerro and A. Herzig (Ed.) Conditionals and Artificial Intelligence, Oxford, forthcoming.
3. Chisholm, R. M., 1974, ?Practical Reason and the Logic of Requirement?, in S. Körner (Ed.) Practical Reason, Oxford, Blackwell, 2?13. Reprinted in J. Raz (Ed.) Practical Reasoning, Oxford University Press, 1978, 118?127.
4. Hansson, B., 1969, ?An Analysis of Some Deontic Logics?, Nous, 3, 373?398. Reprinted in R. Hilpinen (Ed.) Deontic Logic: Introductory and Systematic Readings, Riedel, 1971, 121?147.
5. Føllesdal, D. and R. Hilpinen, 1971, ?Deontic Logic: An Introduction?, in R. Hilpinen (Ed) Deontic Logic: Introductory and Systematic Readings, Reidel, 1?35.