D. Beneventano, S. Bergamaschi, и C. Sartori. LOGIDATA+: Deductive Databases with Complex Objects, том 701 из Lecture Notes in Computer Science, Springer, (1993)
D. Beneventano, S. Bergamaschi, и C. Sartori. FQAS, том 62 из Datalogiske Skrifter (Writings on Computer Science), стр. 167-187. Roskilde University, (1996)