1. K.R. Apt & M.H. van Emden, Contributions to the Theory of Logic Programming, J. ACM 29 (3), pp. 841–862, 1982.
2. J.C.M. Baeten, J.A. Bergstra & J.W. Klop, Priority rewrite systems, report CS-R8407, Centre for Math. & Comp. Sci., Amsterdam 1984.
3. J.C.M. Baeten, J.A. Bergstra & J.W. Klop, Term rewrite systems with priorities, in: Proc. 2nd Conf. on Rewriting Techniques and Applications, Bordeaux 1987, Springer LNCS 256, pp. 83–94, 1987.
4. M. Fitting, A Kripke semantics for logic programs, Journal of Logic Programming 4, pp. 295–312, 1985.
5. J.W.Lloyd, Foundations of logic programming, Springer 1984.