1. [Clocksin & Mellish 1981] W.F. Clocksin and C.S. Mellish "Programming in Prolog " Springer-Verlag 1981. [Clocksin & Mellish 1981] W.F. Clocksin and C.S. Mellish "Programming in Prolog " Springer-Verlag 1981.
2. ] F. Pereira, "Extraposition Grammars;Pereira;American Journal of Computational Linguistics,1981
3. ] F. Pereira and D.H.D. Warren, "Definite Clause Grammars for Language Analysis--A Survey of the Formalism and a Comparison with Augmented Transition Networks;Pereira;Journal of Artificial Intelligence,1980
4. [Sterling & Shapiro 1986] L. Sterling and E. Shapiro "The Art of Prolog " MIT Press 1986. [Sterling & Shapiro 1986] L. Sterling and E. Shapiro "The Art of Prolog " MIT Press 1986.