1. S. Abiteboul, S. Grumbach, “Une Approche Logique de la Manipulation d'objets Complexes”, 3e Journees BD3, Port Camargue, 1987.
2. S. Al-Amoudi, D. Harper, “On Compiling Logic Programming Languages into Conventional Relational Algebra Operations”, Tech. Rep. University of Glasgow, UK, 1987.
3. K.R. Apt, H. Blair, A. Walker, “Towards a Theory of Declarative Knowledge”, Proc. of Workshop on Foundations of Deductive Databases and Logic Programming, USA, 1986. Also in J. Minker, editor, Deductive Databases and Logic Programming, Morgan Kaufmann.
4. F. Bancilhon and S. Khoshafian, “A Calculus for Objects Calculus”, Proc. PODS1986.
5. C. Beeri et.al, “Sets and Negation in a Logic Database Language LDL1”, MCC Rep, 1986.