1. The complexity of unification;Baxter,1977
2. The undecidability of the third order dyadic unification problem;Baxter;Inform. and Control,1978
3. Programming in POP-2;Burstall,1971
4. L'anatomie de Prolog II;Van Caneghem,1984
5. Prolog II, manuel de référence et modèle théorique;Colmerauer,1982