1. Al-Hibri, A., 1978,Deontic Logic (University Press of America, Washington, D.C.).
2. Castañeda, H.-N., 1970, ?On the Semantics of the Ought-to-Do,?Synthese 21, 449?468.
3. Feldman, F., 1986,Doing the Best We Can (D. Reidel, Dordrecht).
4. Føllesdall, D. and Hilpinen, R., 1970, ?Deontic Logic: An Introduction,? in Hilpinen, R. ed.,Deontic Logic: Introductory and Systematic Readings (D. Reidel, Dordrecht), 1?35.
5. Goble, L., forthcoming, ?A Logic ofBetter,?Logique et Analyse.